(CNN) -- European heavyweights AC Milan and Real Madrid fought to a 1-1 draw in the San Siro on Tuesday which leaves them level on points at the top of Champions League Group C.

Real coach Manuel Pellegrini has been under pressure for his job after their 3-2 reverse to the Italians in the Bernabeu last week, but his side responded with a strong performance.

The Spanish giants took a deserved lead in the 29th minute as Brazil ace Kaka charged past Clarence Seedorf before sending in a shot which Dida could only parry to Karim Benzema who slotted home.

The lead did not last long as Gianluca Zambrotta won a penalty as his cross hit the arm of the blocking Pepe.

Real's players protested the award and paid the full price as Ronaldinho blasted the penalty past Iker Casillas.

Milan's Pato had a goal ruled out by referee Felix Brych as he celebrated and late on substitute Raul brought a superb save from Dida as the game ended in stalemate.

It leaves both teams on seven points, just one point clear of Marseille who boosted their hopes with a 6-1 rout of FC Zurich.

Midfielder Silvan Aegerter's own-goal in the third minute set the scene and the Swiss side were two down when Fabrice Abriel doubled the lead in the 11th minute with a free kick.

Visiting striker Alexandre Alphonse cut the lead in the 31st minute, but Marseille captain Mamadou Niang restored a two-goal lead six minutes into the second half.

Vitorino Hilton, Benoit Cheyrou and Brazilian striker Brandao completed the rout in the last 10 minutes. Zurich are bottom of a tight group on three points.

Chelsea clinched their qualification from Group D with a dramatic 2-2 draw at Atletico Madrid.

Didier Drogba returned from a three-game suspension scored twice in the final 10 minutes to put the visitors 2-1 ahead, but Argentine striker Sergio Aguero grabbed his second with a 90th minute equalizer.

"It was a good game but frustrating because we didn't win it," said Drogba.

"We have qualified which is great although it would have been nice to do it with a win."

Aguero put struggling Atletico ahead in the 66th minute with a tremendous strike, but Ivory Coast star Drogba headed an equalizer on 82 minutes and was on target again two minutes from time.

Porto joined Chelsea in the knockout stage as a late goal from Falcao saw them win 1-0 at APOEL Nicosia.

The Colombian striker scored in the 85th minute with a low shot to leave his side one point behind Chelsea at the top with two games remaining.

Atletico have two points and APOEL are on one to be left battling for a UEFA Cup spot.