“I’m a jigsaw puzzle,” Santi Cazorla says. There is a bit of his left forearm on his right ankle, a piece of thigh in its place and the back of a leg in one heel. There is also a grin on his face, somehow. There is a metal plate in a foot and a new achilles, made from rolled-up hamstring, occupying the space where the rot set in. He points to the body parts that are where they are not supposed to be, a player for whom “patched up” applies literally, a tale told by tattoo: it says “I, n, d …” on an arm and “… i, a” on an ankle, his daughter’s name cut in half and grafted on, artery and all, where there was once a hole – a window into the horror below.

One day, you may read about Cazorla in medical textbooks. “Mikel Sánchez, the surgeon, puts me in his talks, a case study,” he says. “He and the physios say they’ve never seen such an extreme case.” There were knee, foot and ankle injuries, targets missed, seemingly endless setbacks, and 10 operations; beneath the skin, splitting open and exposed, an infection consumed 10cm of tendon leaving the bone squishy, risking his leg and his career.

Arsène Wenger said it was the worst injury he had seen and a doctor told Cazorla to settle for walking around the garden. “I’m a football nut,” he says, and for 636 days he did not play. Most thought he never would. There were nights where, lying alone a long way from home, he gave up. “I’d talk to my family and say: ‘It’s over. Tomorrow I’ll tell Juancar, the physio: I can’t go on, pal.’” But here he is, just finished training. He has started all three of Villarreal’s games this season.

“I have to pinch myself when I think: ‘I’m playing Saturday.’ I appreciate it all, every moment. I understand players thinking it’s a pain to be stuck in a hotel the night before but I’ve been in hotels alone, hospitals too. I’ve fought for this.”

Part of Cazorla’s left arm has been grafted on to his right foot, splitting the tattoo of his daughter’s name. Photograph: Pablo Garcia

It goes all the way back to a knock in a friendly against Chile in September 2013 but that does not tell the story, and it need not have come to this, a culmination of factors over five years.

He cracked a bone in an ankle, suffered a knee ligament injury in November 2015 and played in increasing pain until facing Ludogorets in October 2016. “Half-times killed me, because it got cold, I’d be crippled at the start of the second half and the pain got worse and worse,” he says. “That night, I cried; it had become too much. I had to stop. Then the problems started.”

“It’s not a big injury,” Wenger said then but Cazorla did not play for Arsenal again. His skin had deteriorated and split open and infection attacked.

They did a skin graft but they didn’t see what was inside – the bacteria eating away, eating away

“I picked it up in the operating theatre and then there was the fact that the wound was open,” he explains. “I’d work on the bike and a couple of stitches would come out. Because it was an open wound, bacteria can enter, so another bug gets in. At night, a yellow liquid would come out. Every time they sewed me up, it split again; more liquid. They did a skin graft but they didn’t see what was inside – the bacteria eating away, eating away. They never found out which bacteria it was.

“They’d said to me: ‘Don’t worry about playing football, concentrate on regaining a normal life, being able to play with your son or go for a stroll.’ But I didn’t attach too much importance to that because by then I’d already decided to come to Spain, where they told me completely different things.

“I’d got tired – I’d gone through two or three months of operations. I went to Vitoria the next day and that’s when they found the bacteria – two in the tendon and another in the bone.

A mobile phone image shows the injury Cazorla suffered. Photograph: Pablo Garcia

“They didn’t know how much of the tendon the infection had eaten,” Cazorla continues, tracing a line up his leg, stopping at calf, knee, thigh. “Mikel said: ‘I’m going to have to open you up until I find the tendon.’ They told me they’d have to open, open, open, open and when they did, they saw I had lost 10cm. I’d been lucky, they said, it could have been more. When he had to rebuild the tendon, he realised how bad a condition the bone was in. He could put his finger in it. It was like Plasticine. That’s even more dangerous.”

The discovery was relayed back. “They [doctors in the UK] said: ‘We know.’ They said it was under control. ‘We gave you antibiotics.’ But giving antibiotics isn’t the same as giving the exact antibiotic for each specific bug. They didn’t know which bacteria were eating the tendon.”

Cazorla spends most of the time laughing but there must have been anger. A sense of blame. Amputation had been a risk, after all. Could he even have taken action? “My family said that but people said it’s not worth it. You can feel frustrated because if they’d seen it the first day, the problem would probably have been minimal but I didn’t see how it would fix anything. It’s a huge hassle and it wouldn’t do any good to fight over medical issues.

Cazorla’s patched-up right foot. Photograph: Pablo Garcia

“They never took responsibility or said sorry, that they hadn’t realised. I’m convinced they think they did the right thing, that it wasn’t because of the bacteria that wasn’t spotted, that it was just bad luck. I don’t think they feel guilty. And Arsène always supported me. He renewed my contract before the first operation, which was an incredible gesture. He called me in: ‘Santi, I’m going to give you the optional year. It’s here, sign it, have your operation with peace of mind.’ That helped me focus on my rehabilitation without fear. I’m eternally grateful for that.”

It is natural to wonder what might have been had different decisions been made, all the way back to Chile. “I don’t blame myself but it’s true the kick comes in the 20th minute and I played 90. I often think: ‘By not being selfish, not thinking of yourself, you made the injury worse.’ If I’d said: ‘Take me off’ … People told me I should have been smarter but I’m not going to be selfish. Arsenal asked: ‘Why didn’t you get subbed?’ But they respected my decision. When the crack showed, it was suggested I stop a while and I refused – it’s a knock, put a bandage on, and the next week I played.

“There have been people who maybe didn’t act the right way – maybe I wouldn’t have had to go through half these problems – but I’m the one who decides who to work with, where, how. I could blame people but in the end it’s me. I should have come to Spain the first day.”

When he did, Sánchez reconstructed Cazorla’s tendon using the semitendinosus muscle cut from a hamstring and inserted a plate in a heel. “In London they had pretty much decided I wasn’t [going to play again]; in Spain they said: ‘Santi, it’s bad, pretty screwed up, but we’re going to fight.’” Cazorla left his wife, Ursula, and two kids in London, and travelled for treatment in Vitoria and rehabilitation in Salamanca – an anonymous, silent, lonely and laborious existence. Progress was slow and more procedures followed; at one point, the improvised tendon had to be disentangled from the tissue around it and reattached.

Cazorla in action for Villarreal against Girona. ‘I don’t feel too bad; I’m optimistic,’ he says. Photograph: Domenech Castello/EPA

“At times, I’d be ready to give up. It’s hardest when you don’t see any improvement. I’d talk to the medical staff again and they’d say: ‘Do you want to play?’ ‘Yes.’ ‘Right, so that’s that. Today, we work. Tomorrow, you’ll see.’ And I’d start to see tiny things. One day you get on to a pitch and your mind clears. Wow! You go back to the hotel with a huge smile. The physios were clever, they ‘conned’ me. They’d give me a ball and … madre mía! It made me feel a tiny bit like a footballer again. And they’d say: ‘Tomorrow, more ball work.’ And with those little tricks, it was worth getting up the next day.

“My family would call: ‘I touched the ball.’ ‘And how was it?’ ‘It hurt but I touched the ball!’” Back in London first and Oviedo next, India, now five, and Enzo, eight, grew older. “The kids changed schools three times in a year and we didn’t even know if it would be worth it. I’d arrive home for one night and the next day they’d already be saying: ‘Papi, you’re leaving again, aren’t you?’ They came to see it as normal and that killed me. But I did it for them too because my son’s football crazy too.”

Cazorla points; it’s hard not to be drawn, again, to the scar on one arm. On the pitch below, Enzo thumps a shot against the post. “He said to me: ‘Are you not going to play any more?’” Cazorla says, puffing out his cheeks. “‘Yes, yes, I’m going to play, of course.’ ‘With that foot?! It looks a bit strange, eh.’ I said: ‘Well, it’s different. Best not to look at it too much.’ Now he watches me play and it makes me very happy to see him in the stand.”

Cazorla was unveiled as Villarreal player from inside a smoke-filled chamber, with the help of a magician. Photograph: Villareal CF TV

Enzo wears a yellow Villarreal kit, “Papi 19” on the back. His dad briefly trained with Alavés’ youth team but by the summer, aged 33, he was unemployed. He joined Villarreal in pre-season and eventually signed. Cazorla falls about giggling explaining his presentation, a magician making him dramatically appear inside a smoke-filled chamber. “I was hidden: 45 minutes in a tiny space, sweating, and my back was hecho un cristo, a right state,” he laughs. “I said: ‘Hey, the presentation was great and all but I can’t play Saturday now.’”

Instead, he started then and every game since. There is pain, a certain lingering fear, a weakness in his ankle and an imbalance in his body, weight loaded through one side, but he says: “I don’t feel too bad; I’m optimistic.” He has a one-year contract with an optional second but no plan: “Just play the next game, then try to play the next.” And do so for as long as he can. He has been arguably Villarreal’s best player.

Not being able to say goodbye playing at the Emirates is like a thorn in my side

Could it not have been with Arsenal? “No, they didn’t want to,” he says. “They were very good, very honest. My idea was to do at Arsenal what I eventually did here. I knew whoever was going to sign me would have to see me first: nobody just gives you a contract. Pre-season with Arsenal, let them see me, then we all decide. But they couldn’t wait to finalise the squad. They said they’d help any way they could otherwise. I understood it, respected it. I’m eternally grateful.

“The people love me there and I’ll always have a connection with Arsenal, so much affection. Not being able to say goodbye playing at the Emirates is like a thorn in my side. If I had to leave, I wanted it to be in front of the fans.”

He has been invited to the Arsenal Legends game against Real Madrid Legends on Saturday. To play? “No,” he shoots back, laughing, “it’s for ex-players and I don’t think I’m there yet.”

So, Ludogorets, 19 October 2016, was the last time. Except, that is, one night in April, when he “trained” on the Emirates pitch before the Europa League semi-final with Atlético Madrid. There was nostalgia in his request. “I asked if I could because I didn’t know if I would play again. It was nothing much really: four laps, dribble a bit, but just being there again on that grass, just to feel the warmth of the crowd was lovely. To think: ‘I’m going to take something with me, even if I don’t play again.’” But Santi Cazorla did play again.