Henry is currently struggling with a troublesome hamstring as well as a foot problem, and was given a pain-killing injection to play in the first leg a fortnight ago.

It is the latest in a series of niggling fitness problems Henry has endured after a gruelling finish to last season, which ended with defeat in both the final of the Champions League and World Cup.

Although Togo striker Emmanuel Adebayor will be available despite his domestic suspension as Arsenal look to overcome a 1-0 deficit to progress to the quarter-finals, they could certainly do with their talisman available against the Dutch league leaders.

Wenger, however, remains cautious over Henry's likely involvement.

"His chances are 50-50, not more than that," the Arsenal manager said.

"He will not train at all but we will risk him by including him in the 18. Whether he starts or not, I do not know, he will have a test on Tuesday.

"I do not think we will give him another injection because that did not work last time."

Henry is desperate to get back into action and feels he is 'paying the price' for continuing to play on earlier in the campaign when not physically ready.

The Arsenal captain revealed his frustration at having to watch from the sidelines in his programme notes for Saturday's game against Reading.

"It is difficult to handle at the moment because I am not used to being injured," Henry wrote.

"Perhaps it was due to happen to me, though, because since I arrived at Arsenal I have not really had that.

"I think I made a mistake at the beginning of the season when I played while not fully fit after the World Cup. I guess I am paying for that now.

"I always knew this would be a difficult season for me physically, but I did not expect to have so many niggling injuries.

"After the Middlesbrough game I thought I was back to my best, but then that kick on the foot I got there set me back."

As well as Adebayor, defenders Kolo Toure and Emmanuel Eboue will be available to face PSV as their suspensions do not apply to UEFA competitions.

In-form midfielder Tomas Rosicky is expected to need another week or so for his groin injury to fully heal but, with resources stretched, Theo Walcott looks set to have to wait for surgery on a shoulder problem.

Although Wenger is not expecting Ronald Koeman's men to come out all guns blazing at the Emirates Stadium, he remains confident Arsenal can break down the Dutch side to secure the required result.

"I think we can score against them, but it is important for us to feed our strikers and give them some support," he added.

"It is part of the learning process, but we will not have that number of chances against PSV.

"On Saturday, Reading came here with nothing to lose but PSV will be much more defensive. I do not expect them to attack us."

Adebayor, meanwhile, will discover the result of a charge from the Football Association at a personal hearing tomorrow.

The 21-year-old was shown a red card following the mass brawl at the end of the Carling Cup final against Chelsea.

He is already serving a three-match domestic ban as a result and could face further sanctions for "reacting aggressively and failing to leave the field of play immediately after being sent off".