Forget Cristiano Ronaldo, Paul Parker believes Carlos Tevez is the key to Manchester United's defence of their European crown.

More Stories

• Champions League team news
• Fergie fury as Terry is let off hook

"It has to be said, United are not in the greatest shape heading into their first Champions League clash of the season.

The new domestic campaign has not started as well as expected and the defeat to Liverpool at Anfield - which prompted Alex Ferguson to lament his side's "Conference defending" - only compounded matters.

But of course, the season is young and United have yet to be unleashed on European competition. What's more, they still have plenty in reserve and despite their slow start domestically, the holders will once again be a force to be reckoned with in Europe.

Ironically, I think it was Dimitar Berbatov's long, drawn-out arrival at Old Trafford that did most to disrupt United's pre-season preparations. Yet their chances of European success could depend on how well the Bulgarian adapts to life at United.

Another eight-goal haul from Cristiano Ronaldo is unlikely, so goals will have to come from another source. Clearly, the Bulgarian target man has been brought in to fill that role.

I was a big fan of the way he played at Tottenham and I believe he can be a huge success at United, but only if his team-mates play to his strengths. And that means getting the ball out wide and giving him the service he craves.

Traditionally, one of United's strengths has been their natural width, but at the moment they are lacking somewhat in that department.

As a result so far in the Premier League this season they have been rather easy to contain. But with Ronaldo on his way back, as long as the Portuguese plays wider than he did before his stint on the sidelines, Berbatov can be sure of some good service.

But at the same time, Ronaldo's return poses a real problem for Alex Ferguson - albeit the kind of problem that most managers would give their right arm for. With Ronaldo, Berbatov, Wayne Rooney and Carlos Tevez all vying for a place in the same line-up, United boast an embarrassment of riches.

It's no secret that to win the Champions League, a squad needs strength in depth - and that is exactly what Berbatov's arrival has given United.

But the temptation will be there to squeeze all four jewels into the crown. And that could well cramp their style and negate their individual effectiveness. If that kind of formation is considered too attacking for the Premier League, then it is certainly unsuitable for the Champions League.

How Ferguson deals with his team selection will have a huge bearing on how United's European campaign pans out this season. It's a real conundrum, and one that I don't envy him having to deal with.

But I would make sure Tevez is included, every time. The Argentinian is a big game player and he, along with Anderson in midfield, have the ability to raise the tempo of a game - something that is needed in European football.

Too often United have tried - and failed - to alter their style and match European opposition at their own game by playing a slower-paced, more continental game.

But with the South American duo in the side, United look more dynamic and likely to take the game to the opposition. And that could be crucial to any success United can enjoy in European this season."