Previews - Aston Villa v Chelsea Arsenal v Charlton: There is little love lost between Martin O'Neill and Jose Mourinho but last night the Aston Villa manager launched a robust defence of the Portuguese, saying he has already answered all the questions the Premiership has asked of him.

Two successive draws and eight goals conceded in the last four games have put the Chelsea manager under the spotlight but O'Neill said criticism of Mourinho is unjustified ahead of tonight's meeting at Villa Park.

The Derry man, who had been strongly critical of the time-wasting tactics employed by Mourinho's Porto side when Celtic were defeated in extra-time in the 2003 Uefa Cup final, believes the Chelsea manager could walk away from football at any moment completely satisfied with his achievements.

"He's proved himself at the top level," said the Villa manager, "and if his career was to end tomorrow morning, it's been glorious."

With Chelsea seven points behind Manchester United, Mourinho appears to be facing the most exacting period of his Stamford Bridge reign. However, O'Neill rejected the notion that Mourinho's ability to manage has never before been challenged in the Premiership.

He believes the relentless pace Chelsea have set in the previous two seasons under Mourinho has not been given the praise it merited and masks the pressure he was already under.

"I totally disagree that Jose Mourinho is facing his first test," O'Neill said. "He stepped into a new environment, it didn't matter that he had the wherewithal - it's great to have great players at your disposal and also great that you know you can bring them in. But you still have to manage them.

"Chelsea have gone on and taken the league championship by storm the last two years but you still have to go and battle, so for people to say that this is his first test, I utterly disagree.

"I think he has come through all those tests before, and just because Manchester United are in front of them it doesn't mean that he is under that sort of pressure. I believe that if you are good enough to race clear at the start of the season then you deserve all the credit in the world for doing that."

O'Neill, who believes Chelsea could "with a bit of luck" win all three domestic competitions and the Champions League this season, said Mourinho's success is all the more commendable because he failed to make the grade as a player.

"We all aspire to be the best player in the world but he didn't aspire to anything," said the Villa manager. "That makes it all the more praiseworthy that he has managed to get the very best players to play for him."

Villa go into tonight's match bidding to end a run of nine matches without a win. Their hopes ought to be improved by the absence of John Terry, but O'Neill is not certain his side can capitalise on Chelsea's defensive frailties.

"Even the great teams like Chelsea will miss John Terry," he said. "Whether we are capable of doing something about that is another question."

Meanwhile, Arsene Wenger is considering reinstating Thierry Henry to the Arsenal line-up for the first time in more than a month against Charlton tonight after Arsenal were struck by a forwards injury crisis.

Arsenal's 1-0 defeat at Sheffield United on Saturday caused them to suffer more than missed points, with Julio Baptista and Robin van Persie both likely to join Emmanuel Adebayor on the injury list.

The Bramall Lane defeat has left Arsenal outside the Champions League positions and Wenger searching for options up front, with Jeremie Aliadiere the only other match-fit striker.

Theo Walcott is still nursing a back problem and the paucity of available players could cause the Arsenal manager to accelerate Henry's return. The Arsenal captain has been absent since November 29th after sciatica reduced his mobility with hamstring and neck damage.

Without him Arsenal recorded wins over Tottenham, Wigan, Blackburn and Watford but Saturday's reverse makes victory in this encounter with Charlton a necessity.

Henry had been targeting next weekend's FA Cup third-round tie against Liverpool for his comeback but Arsenal's need appears more pressing.

"We have to assess the situation as late as possible," said Wenger. "At the moment it is difficult to say. It looks like Emmanuel Eboue will not be back. (Alexander) Hleb, (Johan) Djourou and Henry I don't know.

"Adebayor will still be out. We have a few uncertainties from Sheffield United.

"Van Persie got a knock on his ankle. Baptista will be out definitely; he had a kick and has a bad ankle. Hleb certainly has a chance. Henry I will see."

Wenger conceded his team lacks the consistency required for a title challenge but, with Bolton, who recorded five consecutive wins prior to yesterday's defeat at Anfield, and Portsmouth mounting credible campaigns for Champions League qualification, the stakes for a top-four finish have also risen. Last year Arsenal pipped Spurs for fourth spot on the very last day of the season

"It looks like the other teams have broken into it," he said. "We need far more consistency to achieve it."

• Guardian Service