Chelsea are to scrutinise the ankle damage sustained by Demba Ba, an injury that forced the Senegalese from the fray at half-time against Sunderland, as their squad continues to strain under the weight of fixtures across three competitions.

Victory over Sunderland in the 57th game of their campaign restored Rafael Benítez's team to third in the Premier League, with the week ahead seeing them take a two-goal advantage from the first leg to Moscow against Rubin Kazan in the Europa League and an FA Cup semi-final against Manchester City at Wembley. The interim first-team manager lost Ashley Cole last week and Gary Cahill just before the recent international break, to injury and has been left sweating over Ba's fitness.

The Senegalese was clattered by Sunderland's Craig Gardner midway through the first period and, although he completed the half, was replaced by Fernando Torres at the break. "When you make a change at half-time, it's never 'fine'," said Benítez. "It's too early to say how serious it is but it's a problem with his ankle. We'll see on Monday. The tackle was a heavy tackle but we don't know now."

Ba, a £7m signing from Newcastle in January, is ineligible for the Europa League and so would have been omitted from the squad for Moscow regardless, but any prolonged absence would place the onus back on Torres to perform every week, as he did before Christmas. The Spaniard made an instant impact here as Chelsea secured the third home victory of a busy week, with Benítez convinced his players have benefited from a lack of antagonism from the crowd in recent weeks over his presence.

"I just try to concentrate on my job but, as people keep suggesting, the feeling is everybody has realised we have to stick together and support the team," said Benítez, who had voiced his frustration at the dissent to which he had been subjected after the FA Cup fifth-round victory over Middlesbrough in February. "That was my message before, and that is still my message now. It's always important [the atmosphere]. When you have great game, it's the atmosphere. The best nights here are with great atmosphere. It's always very positive, so it's important to have everyone sticking together and pushing in the same direction. That's clear."

Should Chelsea continue to progress into the Europa League and FA Cup finals, there remains the possibility Benítez's side will have to play Manchester United, Tottenham Hotspur and Aston Villa in the six days before the showpiece at Wembley, with the Spaniard resigned to the race for the top four stretching until the campaign's last day.

"I don't think it would be possible [to secure a top-four finish before then] because Spurs and Arsenal are still there pushing, Everton as well," he said. "We have to continue to the end. Hopefully we can do well in the cup competitions and then be ready for Fulham and Liverpool. But we cannot stop now. We have to stay on our toes because we have another four big games now coming up."