Cometh the Arsenal defensive crisis, cometh the ex-Manchester United centre-back.

It may have been an unthinkable state of affairs just a few months ago, but with three of the Gunners' first-choice back four unavailable through injury, Mikael Silvestre will take on a pivotal role as the Gunners feel the full force of 50,500 fans in the Sukru Saracoglu Stadium here in Istanbul.

The Frenchman made 249 appearances for United in a nine-year spell and watched from the substitutes' bench as Sir Alex Ferguson's side lifted the Champions League trophy in May.

Tonight marks the 31-year-old's first European outing for his new club and his importance could not be more of a contrast from the peripheral figure he cut in Moscow.

Silvestre has played in the Champions League on 70 occasions 64 with United and six with Inter Milan which represents a wealth of experience compared with the rest of the rearguard.

The likely starters at the back Emmanuel Eboue, Alex Song and Gael Clichy have just 55 games in the competition to their names between them.

Even Manuel Almunia, who will captain the side, has featured in just 17 Champions League matches and has never played in the intimidating atmosphere of Istanbul before.

With William Gallas, Kolo Toure and Bacary Sagna all ruled out and Johan Djourou likely to only be fit enough for a place among the substitutes, Silvestre finds himself as the defensive linchpin of a side he only made his debut for three days ago.

After a shaky start, the Frenchman snuffed out the threat of striker Yakubu as the Gunners came from behind to beat Everton 3-1 at Emirates Stadium.

And manager Arsene Wenger admitted his relief that the free summer signing from Old Trafford had come through unscathed after shaking off a persistent hamstring problem. "I am happy to have him," said Wenger.

"He is the one who can lead the defence because he has played on every single pitch in Europe. He is a very professional guy and very kind as well. I am confident he will be the guide of the back four.

"We will start the game at the back with the same four that ended the match against Everton."

Arsenal are expected to line up in their usual 4-4-1-1 shape to combat Fenerbahce's 4-1-4-1 system. The hosts are a curious threat. Lying 10th in the Turkish top flight after their worst start to a league campaign in 20 years, the team nicknamed the 'Yellow Canaries' have yet to take flight domestically or in Europe.

Their listless 3-1 defeat at Porto was followed by a disappointing goalless draw at home to Dynamo Kiev and they had to battle back from a goal down to beat Kocaelispor, the Turkish Super League's bottom team, on Saturday.

But Wenger is still wary of the threat they pose. He said: "They have top-class players in every position and that's why it will be a big challenge for us. It is important for us to start strong and not to give them any confidence."

Fenerbahce's poor form is surprising given the notable coup in appointing Luis Aragones as manager following his success with Spain at Euro 2008.

Four players came in and eight went out over the summer as the 70-year-old overhauled his squad and Wenger dismissed the notion his opposite number was under pressure in his first job outside his native Spain.

"I hadn't heard about that," he said of the man who he has now "forgiven" for infamously making a racist comment to Jose Antonio Reyes about Thierry Henry in 2004. "Look at our faces we are always under pressure.

"You need at least six months to have an impact on the way the team plays.

"They are a team with a lot of players who have offensive potential. They have [Daniel] Guiza and [Semih] Senturk who are very dangerous going forward so we expect them to put us under pressure."

This is also a side who have not lost in four years and 15 matches at home in the Champions League, including last season's 2-1 victory over Chelsea in a quarter-final tie they eventually lost 3-2 on aggregate at Stamford Bridge.

Weathering the early storm is key to the Gunners' hopes and that will be when Arsenal's youthful side will turn to the older heads for reassurance.

United manager Ferguson commented when Silvestre signed a new contract in August 2006 that his "experience at the club will help the younger players as they develop and he has a central role to play". But like the rest of us, not even the great Scot thought that would end up being the case at Arsenal.