Playing one of your domestic rivals in the Champions League is a strange experience. We had 10 games over five seasons against Chelsea and the atmosphere and intensity of those contests made it feel as if they were Continental opponents.
Up for the battle: Ivanovic squares up to Nani in their encounter at Stamford Bridge earlier this season
The same was true when we played Arsenal. In the first leg, the away side are always cautious, even when they are losing 1-0 with 10 minutes to go. If that was the case in a Premier League match, you would throw everything forward in search of an equaliser but in Europe, you just make sure 1-0 doesn't become 2-0.
Liverpool lost 1-0 at Stamford Bridge in the first leg of the semi-final in 2007, remember, but we still managed to turn it round at Anfield and reach the final in Athens, albeit with the help of a penalty shootout.
So it will be very interesting to see what tactics Carlo Ancelotti and Sir Alex Ferguson deploy this evening at Stamford Bridge. Chelsea have been playing 4-4-2, and Manchester United used that formation when the sides met at the same ground last month.
That was the first time in a long while that United have played like that away from home, yet it almost paid off. Chelsea might have emerged from that controversial game with three points but it was impossible not to acknowledge that United were unlucky.
I wouldn't expect United to be so cavalier from the start here and it wouldn't surprise me if both sides played 4-3-3 in the away legs. It will be like watching a game of chess at times, as neither side will want to surrender an inch before the return at Old Trafford.
ONE TO WATCH Nani: The Portuguese winger has had a terrific season, and the right back position for Chelsea in the last two years has been a bit of problem. Sir Alex Ferguson played Cristiano Ronaldo on the left wing in the Champions League final in Moscow in 2008 because Michael Essien played right back. Nani has the pace and trickery to take advantage.
One of the pivotal contests will bebetween John Terry and Wayne Rooney. I'm a huge admirer of John, he's aterrific defender; one of the best I have ever seen. He will be bracinghimself for the searching examination Wayne will give him over 90minutes.
Wayne'shat-trick at the weekend showed he is coming into form and John won'tbe able to switch off for a second, as we know the emotions that areattached to conceding an away goal. If United were to take the lead ina league game, Chelsea would just get on with it.
In Europe, an away goal takes the windout of your sails. John is like me, he hates it when his team do notkeep a clean sheet and he won't be letting Wayne out of his sight. Insome ways, it is almost impossible to call who will go through.
There is nobody better than Ferguson for rotating his squad and even though United are chasing trophies on three fronts, he will have his players conditioned for each game. They also have the winning habit right now.
This, however, is a massive chance for Chelsea. They have not had a great season by their standards but their place in the top four seems assured. That isn't enough for Roman Abramovich but if Chelsea happen to win the Champions League, nobody will remember their final league position.
We played poorly in 2005 but that never gets mentioned as we won the Champions League. It masked everything. This Chelsea team are running out of chances to win the prize they want more than anything, which is why they will throw everything into these games.
THE KEY CLASH: FERNANDO TORRES AND/OR DIDIER DROGBA v NEMANJA VIDIC
This is a big decision for Carlo Ancelotti. If he reverts to 4-3-3, he can play only one of his strikers. Torres had great success over Vidic, who remains one of the top defenders in the world, but Drogba is just coming back into form. Both are fantastic frontmen and Vidic will have to be at his best to keep them quiet
Out of focus: Torres (right) is yet to open his Chelsea account after eight games
CARRA'S BIG-MATCH VERDICT: Manchester United. In some ways, this is almost too hard to call but I just think United will snatch an away goal and that could prove to be the difference.
BARCELONA v SHAKHTAR DONETSKCARRA'S BIG-MATCH VERDICT: Barcelona. There is so much pressure on Barca as they try to live up to their tag of one of the best teams of all time. If they win the Champions League this year, it will be their third triumph since 2006 and you can then say they have dominated the competition like the great Real Madrid, Ajax and Liverpool sides of the past. This will not be a formality, as Shakhtar are a top side with nothing to lose, but Barcelona will go through.
ONE TO WATCH
Xavi:The best midfielder in the business and the man who makes Barcelona tick. If he can dictate the tempo a difficult task for Shakhtar will become practically impossible.
KEY CLASH: LIONEL MESSI v DMYTRO CHYGRYNSKIY
Chygrynskiy cost ?22million when he joined Barcelona in 2009 and, provided he passes a late fitness test, will have something to prove after being sold back for ?12.5m 12 months later. That said, he will have his work cut to keep the best player in the world quiet.
John Terry Exclusive: As a player, and a man, Frank is an inspiration Fergie revels in spin attack! Sir Alex takes guard at Lord's as Carlo bats for Torres Get ready for the fireworks! Five classic clashes between Chelsea and UnitedChelsea FC news. features and opinion Manchester United FC news. features and opinion
Explore more:People: Alex Ferguson, Jamie Carragher, John Terry, Michael Essien, Xavi, Fernando Torres, Lionel Messi, Cristiano Ronaldo, Nemanja Vidic, Didier Drogba, Wayne Rooney, Roman Abramovich, Nani, Carlo Ancelotti Places: Barcelona, Moscow, Liverpool, Athens, Europe