by TRAVIS CLARK

There was end-to-end action pretty much everywhere you looked on Matchday 4 of the UEFA Champions League. A couple of high profile matches delivered the goods, with late equalizers in Madrid and Manchester scuttling a Chelsea comeback against Atletico and a CSKA upset of United. After today's results, four clubs — Chelsea, Bordeaux, Manchester United and Porto — are through to the knockout stages.

Atletico Madrid held a 1-0 lead against Chelsea thanks to Kun Aguero's tidy finish in the 66th minute. Cue the antics of Didier Drogba, returning after a three-match ban for his abuse of referee Tom Henning Ovrebo last spring, netted goals six minutes apart to seal what looked like a last-gasp victory. However, Aguero snatched a point for his side when he beat Petr Cech with a beautiful 90 minute free kick and tying the game at 2-2.

The high profile match-up of AC Milan and Real Madrid featured Kaka's return to the San Siro, though the game didn't have the same high-scoring result as the previous outing. There was plenty of controversy after Karim Benzema and Ronaldinho traded goals — Alexandre Pato had the go-ahead goal ruled out for a foul in the build up. Neither side could find a second, and it ended in a 1-1 draw.

Meanwhile, CSKA Moscow took Old Trafford by storm, jumping out to a 3-1 against the Red Devils. But a goal from Paul Scholes drew one back before Antonio Valencia smashed home a goal that deflected off the face of a CSKA player to earn a 3-3 draw for the home side.

In other action, Bordeaux sealed their spot in the knockout round with a 2-0 win against Bayern Munich on the road, while Porto joined them after squeaking by Apoel Nicosia 1-0. Marseille laid the hammer down on FC Zurich 6-1, Vfl Wolfsburg handled Besiktas with relative ease 3-0, while Juventus nicked Maccabi Haifa 1-0.

What did you think of Tuesday's action? Surprised to see so many goals and draws all at once? What was your favorite match of the day? Share your thoughts below.