José Mourinho expects Son Heung-min to miss the rest of the season with a fractured arm and has said that Tottenham’s selection crisis in attack could not be worse before they host RB Leipzig in the last 16 of the Champions League.

Son hurt his right arm during the early stages of Spurs’ win over Aston Villa on Sunday and although the forward completed the game and scored twice, he requires surgery on an injury which leaves the club desperately short of options up front. Harry Kane is not expected to return from a torn hamstring until mid-April and Mourinho struggled to hide his disappointment as he prepared for Wednesday’s first leg against Leipzig, saying the bad news about Son had left his players with broken hearts.

Barcelona's Braithwaite move shows up inequality of a broken system Read more

Shortly after a club statement said the South Korean would be out for a “number of weeks”, Mourinho said: “I’m not going to count on him again this season. If he plays two or three games then it’s because he [the press officer] is very optimistic, but I’m not counting on him.

“The situation couldn’t be worse in terms of options. I think that’s a very obvious situation. There is nothing that you can do. The players are going to give absolutely everything. In some periods I was worried about not having attacking options on the bench. Now I don’t have attacking options on the pitch.”

Mourinho is likely to use Lucas Moura as a stand-in forward against Leipzig – the manager said that the 18-year-old Irish striker Troy Parrott is not ready to make an impact at this level – and Dele Alli, Steven Bergwijn and Giovani Lo Celso will be expected to support the Brazilian.

The challenge for Spurs is finding a way to play without Kane and Son, though it helps that their German opponents have a crisis of their own in defence. Dayot Upamecano is suspended and Ibrahima Konaté and Willi Orban are injured.

Yet Leipzig, a point behind Bayern Munich at the top of the Bundesliga, will provide an awkward test. They are managed by Julian Nagelsmann, a gifted 32-year-old, and the prolific Timo Werner is the danger man up front.

Guardian sport (@guardian_sport) Tottenham's José Mourinho jokes about signing Peter Crouch after latest injury setback pic.twitter.com/L2BqY8fRey

Mourinho, who has not won a Champions League knockout tie since 2014, expects it to be tough. There was a note of defiance from the Portuguese, though. When he replaced Mauricio Pochettino in November Spurs were 12 points behind fourth-placed Chelsea. The lead is down to one point before Spurs visit Stamford Bridge on Saturday.

“You know that I like analogies,” he said. “Sometimes I do good ones, sometimes I do silly ones. When we arrived we were on the minus-12th floor. We got to the stairs and we started climbing. But immediately at the beginning the stairs broke. We found a way, we started climbing and we started going and going and going … 11 steps, 11 floors, we go and when we are arriving on the fourth floor somebody came and took the stairs away.

“Now we are in trouble. We are with our arms on the balcony on the fourth floor and now we have two options: one is to give up and fall and normally die because it’s the fourth floor. Another way is to fight with what we have – no stairs, but arms.

The Fiver: sign up and get our daily football email.

“We are going to be on that balcony fighting with everything that we have and there is only one possibility of help in this incredible fight we have ahead of us: our public. No strikers, no market, no players, nothing. The only help we can have now, especially playing at home, is our crowd.”

Last season’s beaten finalists looked for cover for Kane in January but attempts to sign Krzysztof Piatek, Olivier Giroud and Willian José ended in frustration. “Analogies apart, are we going to give up or are we going to fight?” Mourinho said. “We know that it’s very unfair for the players because they recovered the 11 points to fourth position in the Premier League.

“Not two, three or four, 11 points, and when they arrive in this moment full of hope, with that challenge in the Premier League, knockout stages of the Champions League, last 16 in the FA Cup, we put ourselves in this privileged situation and yesterday the bad news, the first thing was to break our hearts and the second thing was to break our team.

“But we have to recover from broken hearts. So let’s go with a smile, let’s go strong. I’m not going to give up and probably opponents they are thinking: ‘Wow, now is the time to kill them.’ I don’t think it’s going to be easy for Leipzig to play against us, I don’t think it’s going to be easy for Chelsea to play against us.”