Chelsea received a welcome boost before this evening's Champions League first knockout round, second leg against Olympiacos at Stamford Bridge when Frank Lampard learnt that the red card he received in Saturday's 4-0 victory against West Ham United has been rescinded by the FA.

The England midfield player was sent off by Peter Walton, the referee, for pushing Luís Boa Morte during the first half of the match at Upton Park, but Walton is understood to have admitted that he made an error. Avram Grant, the Chelsea first-team coach, was surprised and relieved.

“Surprised, because the decision was the right decision,” he said. “I think for the FA it's very important to admit when they make mistakes, to show that the game is fair for everybody. I wasn't happy that they didn't do the same with John Obi Mikel against Manchester United, but it's a good start.”

Lampard, who has been sent off only once in his career, was eligible for this evening's match in any case, but with a three-match domestic suspension no longer hanging over him, he will also be available to play in the FA Cup sixth-round tie against Barnsley this weekend and the Barclays Premier League matches against Sunderland and Tottenham Hotspur.

Beating Olympiacos, though, is the priority, as Grant said yesterday. He is not the type of character to roar defiance in the manner of some other high-profile football figures, but yesterday he at least muttered it. Questioned about the pressure on him to lead the team through to the quarter-finals, he welcomed it and almost invited more by repeating that the Champions League is his top target and that of the club. “Of course there is pressure, but I like pressure,” Grant said. “It pushes you to achieve good things.

“The Champions League is the club's priority and mine. We haven't been to a final and as a good team that wants to be bigger, we need to be in a final of the Champions League. It's not easy because there are a lot of good clubs, but it is our priority.”

Olympiacos - a strong team on the counter-attack - are likely to take a cautious approach and wait as long as it takes for an opportunity to score an away goal. Grant expects nothing else and will be wary of pushing too many men forward.

“We attacked in the first game and they defended with all their players,” he said. “Every game we want to attack, so it will be the same tomorrow. And I don't think it will be a draw. But defence is important. We started this year's Champions League with a draw at home, 1-1 with Rosenborg. If this is the result [tonight], we are out. So it's important to score but it's important to keep a clean sheet.”

The Greek team suffered only one defeat in the group stage, away to Real Madrid, and finished second in their qualifying group ahead of Werder Bremen and Lazio, scoring in all three away matches. They have lost only one other match all season, are in second position in the Greek league and have plenty of European experience. Antonis Nikopolidis, the goalkeeper, will break the Greek record of 52 Champions League appearances at Stamford Bridge. “We know their record away and they always score,” Grant said. “It will be a hard game, but we are at home.”

Joe Cole, the England midfield player, echoed Grant's sentiments. “It's an important game, but we're experienced in this type of match and we know what we need to do,” he said. “For us it's about applying ourselves in the right way and being aggressive from the start of the game.

“We are very aware that Olympiacos are a good side, particularly away from home, and we'll respect them. They played really well against us in Athens, but we'll be ready for them.”

— Ruud van Nistelrooy, the Real Madrid striker, is likely to miss this evening's Champions League match at home to AS Roma because of an ankle injury. “Van Nistelrooy is almost certain to miss out,” Bernd Schuster, the Real coach, said. The Holland player is set to join Arjen Robben, the injured winger, and Sergio Ramos, the suspended full back, on the sidelines. Real aim to overturn a 2-1 deficit from the first knockout round, first leg.