Manchester United manager Sir Alex Ferguson played down fears that Rio Ferdinand could miss the titanic Premier League showdown with leader Arsenal after a new injury scare.

England defender Ferdinand limped out of United's 1-1 Champions League draw with Valencia on Tuesday with a hamstring problem which has cast doubt over his availability for next Monday's Old Trafford clash with Arsene Wenger's team.

But Ferguson said afterwards he is confident Ferdinand, who missed the World Cup with a serious knee injury, will be in the team for a match that could go a long way to shaping United's season.

"It's a tight hamstring - not a tear or anything like that," said Ferguson, after seeing his side advance to the Champions League last 16 as Group C winners.

"I'm sure he'll be okay for Monday. He felt it at halftime but wanted to carry on. But we have several days now to make sure he is right."

United is already missing key players due to injury and cannot afford any more casualties during what is a crucial stage of the season.

After Arsenal, Ferguson's team travels to Stamford Bridge to face Chelsea and victory in both games would ensure United will be top of the Premier League at Christmas.

Paul Scholes and Patrice Evra are both nursing minor injuries while Ecuador winger Antonio Valencia and midfielder Owen Hargreaves are long-term casualties.

Former England striker Michael Owen has just returned to training after a lengthy absence.

Anderson's second goal since joining United from Porto in July 2007, which cancelled out Pablo Hernandez's first-half goal, earned his side the point which cemented United's place at the top of Group C on a frustrating night in which the host wasted countless chances at Old Trafford.

It means United will avoid European heavyweights Real Madrid and Barcelona when the draw for the last 16 is made on Dec 17.

However, it will have to improve its finishing before the knockout phase resumes in February. United could be paired with AC Milan or Inter Milan.

"Now will just have to take what we get. Hopefully we will get them (Real Madrid or Barcelona) later on. We can make progress, that's the most important thing," said Ferguson, who is demanding more goals from Anderson.

"He should get more. He's a terrific talent, the boy, great pace and power, a strong boy. We are pleased he got the goal and it may help him."

Ferguson produced a surprise before the game by naming inexperienced 20-year-old goalkeeper Ben Amos in the side ahead of Edwin van der Sar and Tomasz Kuszczak.

"We told him a couple of weeks ago he was playing and he did very well when you consider in our back four we had two young boys," said Ferguson. "His best moments were in the second half. He got better as the second half went on."

Valencia is also through to the last 16 after finishing runner-up in the group, and coach Unai Emery declared himself satisfied with his side's efforts.

"We have to be happy with a 1-1 draw at Manchester United," said Emery. "We showed a lot of character."