Midfielder may be out for four weeks after latest hamstring blowWenger: ‘I put him on and it was not the best of decisions’

Alexis Sánchez has escaped serious injury after the shuddering tackle from Leicester City’s Matthew Upson on Tuesday night and Arsenal hope that the forward could be available for Sunday’s FA Cup tie against Middlesbrough.

The update, though, is rather less positive about Aaron Ramsey, who was forced off against Leicester just nine minutes into a substitute’s cameo with his third hamstring injury of the season.

Arsenal’s medics are continuing to assess the midfielder and, at this stage, it is certain that he will miss the club’s next three games – the third one being the Champions League last-16 first-leg against Monaco at Emirates Stadium on 25 February. But it would be a surprise if he featured much before mid-March.

There is relief over Sánchez, who had returned to the team against Leicester after a minor hamstring injury, which had seen him miss the previous two matches. Upson, the former Arsenal player, lunged in at him in the 29th minute to leave him clutching his knee.

Arsène Wenger said that he wanted to withdraw him at half-time only for Sánchez to insist that he could continue. But Sánchez was peripheral after the knock and he was eventually forced off on 68 minutes.

He tweeted afterwards that “sometimes the love for the game and anxiety to be on a football pitch works against you”. Wenger might be tempted to rest Sánchez against Middlesbrough to save him for the bigger challenges ahead but at least he will be able to count on him.

Ramsey was stony-faced as he walked slowly from the field against Leicester and it was clear that he knew the hamstring problem had flared again. He first injured the muscle this season against Tottenham Hotspur on 27 September to miss three weeks and, when it went again at Galatasaray on 9 December, he was out for almost six weeks.

“It doesn’t look good when a guy stops straight away and sits down,” Wenger said of Ramsey, after the game. “I left him out [of the starting lineup] to be cautious with him. I put him on and it was not the best of decisions. I can’t say it’s not a worry because after a while, the player cannot play with a free mind. He’s not over-played. I don’t know why this is.”