Vieira sustained the injury during Arsenal’s 2-1 Barclaycard Premiership victory at Chelsea Saturday, immediately placing him in doubt for tomorrow’s last-16 first-leg tie.

But Wenger today confirmed: “Patrick’s knee swelled up after the game, but it was just a direct knock. It’s okay today; the swelling has gone down, so he will start the game.”

Wenger took a risk which backfired on Vieira’s fitness for a Champions League group game away to Dynamo Kiev last October – when the Frenchman came on as a substitute but was promptly ruled out for a further six weeks.

This time, Wenger insists he will be taking no such risks on any player’s fitness – especially one of Vieira’s importance – with the title run-in beckoning.

Gilberto and Ashley Cole have both been ruled out of the Champions League fixture in Spain because of injuries.

“Gilberto got another knock on his ankle against Chelsea – the same ankle that he injured against Ireland last week – and this time he will definitely be out,” confirmed Wenger.

“Ashley Cole will also not travel because of his back injury. He had a normal training session today, but the medical staff said it would be a risk for him to travel due to his injury.

“We have left him at home. I wouldn’t take a chance any more like I did before.”

In Gilberto’s absence, Edu is again set to partner Vieira in central midfield.

Fredrik Ljungberg is, meanwhile, set to make his first start since February 1 on the right side of midfield following a rib injury.

The Swede was a late substitute at Stamford Bridge last weekend, and Wenger admitted he would “in an ideal world still be a bit short” for this game.

However, the Swede is needed because Ray Parlour and Sylvain Wiltord are both still ruled out – while Dennis Bergkamp, who is frightened of flying, is not in the squad either.

That means Jose Reyes is expected to partner Thierry Henry up front on his first return to play in Spain since his multi-million pound move from Seville last month.

Provisional squad: Lehmann, Stack, Lauren, Toure, Hoyte, Campbell, Cygan, Keown, Clichy, Vieira, Edu, Fabregas, Toure, Ljungberg, Bentley, Reyes, Henry, Kanu.