Arsenal held on to earn a valuable point in Germany with a 1-1 draw while AC Milan stunned defending champions Barcelona at Camp Nou, 2-2, a last-minute goal allowing them to share the spoils on a thrilling Tuesday night of Champions League action.

Elsewhere, Chelsea got their campaign off to a flying start with a 2-0 win over Bayer Leverkusen sparked by the much-maligned Fernando Torres. Olympique Marseille downed Olympiakos in Greece, 1-0, but Valencia failed to turn their dominance into three points with a 0-0 draw at Racing Genk. APOEL upset Zenit St. Petersburg in a wild match that saw Bruno Alves sent off while Ukrainian powers Shakhtar self-destructed in a 2-1 loss at Porto that saw two of their players tossed. Finally, in a game very few likely cared about, Plzen and BATE drew 1-1.

Late goal stuns holders

Barcelona stand stunned tonight. The champs were caught napping at the start and finish and paid for it dearly by coughing up two big points to an energetic Milan side that frankly didn't deserve them.

Barcelona were ball-watching in the first minute as Alexandre Pato attacked from the kickoff, running right down the gut past rooted defenders to beat a stranded Victor Valdes. With 24 seconds gone, Milan had a shock 1-0 advantage.

It was the fifth fastest goal in the competition's history, and it woke up the home team, who then turned on their passing game to spent most of the next 90 minutes in complete control.

Lionel Messi made one of his amazing runs past three defenders to lay on the equalizing goal for Pedro in the 36th minute, and when David Villa lashed home a 50th minute free that put Barcelona on top, you figured the match was done and dusted.

Milan, however, didn't concede a third, which would have killed the match. Instead, they snatched a completely unexpected point two minutes into stoppage time when Thiago Silva rose above everybody in the box and firmly headed home a Clarence Seedorf corner kick.

There's a takeaway from this game and Arsenal's: Sometimes grit and energy can compensate for a lack of possession. And for Barcelona, there might be warning signs. They are still the best team in this tournament by miles on paper. But they are showing the signs of two intense years at the highest level and may just be starting to slip.

Gunners take what they can get

In Dortmund, manager Arsene Wenger watched from the cheap seats as his young Gunners were soundly outplayed for most of the match. And yet, to paraphrase Sir Alex Ferguson, football is a funny old game. Arsenal probably didn't deserve a share of the spoils but got them anyway. A blown pass from Dortmund's captain Sebastien Kehl allowed Robin van Persie to score a wonderfully opportunistic goal just before halftime and give the Londoners a lifeline utterly against the run of play. It would take Dortmund until just two minutes before time to find the leveler they richly deserved, a superb volley from Ivan Perisic that ducked under the bar into the top right corner.

What happened in between was not pretty viewing for Arsenal fans. The Londoners lacked the ability to pressure Dortmund's defense, failed to control much of the midfield play, and at times looked utterly at sea against a withering attack spearheaded by a man they tried to sign, Mario Goetze.

The bright spots on the field were the play of van Persie - a tireless creator who looks like he deserves to wear the armband - and the solid play of Wojciech Szczesny between the sticks. The young Pole took a lot of ribbing for being on the wrong end of Arsenal's 8-2 drubbing at the hands of United, but no one will be teasing him after a virtuoso performance tonight that saw him make three critical stops under heavy fire.

Arsenal are still integrating Mikel Arteta (solid), Yossi Benayoun (tireless) and Per Mertesacker (brilliant), but they have a lot of work to do before they host Greeks Olympiakos in what passes for the easiest fixture in this wide-open group. They can take pride and a hard-earned point away from this match, but they must also be wary. Dortmund were better, and Wenger's facial expressions in the upper deck were proof he knows it.

Luiz stars in return to Blues

Chelsea labored to a win at home against Bayer Leverkusen, requiring a touch of class from a defender, David Luiz, to snap open the match. It was David Luiz's first appearance this season, and there is no small irony in the fact that Chelsea's second biggest signing of last season has now scored thrice as many goals as their biggest.

Nonetheless, it was Torres who was the instrumental player on the night, perhaps finally snapping to attention after a dismal spell and the ugly revelations that he had criticized his own teammates in an interview on his own website.

Tuesday night, Torres certainly looked as if he wished to make amends with a pell-mell performance that started sharply but then looked as if it would follow what has been a despairing script that ends with him fading out. Not this time, though. While Juan Mata and Daniel Sturridge provided most of the bite, Torres set up both goals with clean, assured passes that hinted at what might yet be to come.

Leverkusen were more obstinate than artful. That said, they were rightly baffled to have Simon Rolfes' goal disallowed early for a foul alleged to be on Omer Toprak. It was a call of the most marginal sort, and had that goal stood, this game might have been far different.

Porto triumph over nine

In Porto, the home team won a wild game against Shakhtar Donetsk that saw the visitors finish with nine men. Shakhtar effectively shot themselves in the foot 40 minutes into the match when Yaroslav Rakitskiy was sent off with a direct red card after a wild, two-footed tackle on Joao Moutinho that left the Ukrainian side's Romanian coach, Mircea Lucescu, screaming at his player, not the referee.

The teams were level 1-1 at that point, Porto having handed Shakhtar the opening goal in a bizarre 12th minute. Hulk slammed a penalty kick against the bar to waste a Porto chance at one end, then Shakhtar raced away for a Willian cross to be completely mishandled by `keeper Helton. Luiz Adriano tapped home the gift.

Hulk atoned for his miss with a spectacular 28th minute free kick that was hit so hard `keeper Aleksandr Rybka could only help it into the top net although he was able to get two hands to the ball. The match-winner was made by James Rodriguez, who set up the Brazilian Kleber in the 51st minute.

Porto should have had more, especially when Dymtro Chyygrynskiy picked up a second yellow card and joined Rakitskiy in an early bath.

The rest: APOEL upsets Zenit

Two frantic minutes added up to a glorious victory for APOEL Nicosia, which stunned visiting Zenit St. Petersburg in Cyprus. After an even first hour, Zenit grabbed the lead through Konstantin Zyryanov, who finished after a great 63rd minute run from Danny, the best player on the night for the visitors.

But APOEL turned the game upside down thanks mainly to Gustavo Manduca. First, Manduca collected a rebound from Ivan Trickovski and leveled the match in the 74th minute; then he sent in fellow Brazilian Ailton, whose curling shot to the far post gave Vyacheslav Malefeev no chance, giving the Cypriots a historic Champions League success.

Marseille continued Olympiakos's winless streak at home against French sides thanks to Lucho Gonzales's 51st minute goal. It was as even a game, as the scoreline suggests, but the Greeks' inability to create goal-scoring chances bit them. Rod Fanni's late red card hurts the French side as they await Dortmund in a fortnight, but their campaign is otherwise off to a solid start.

How Valencia didn't take three points in Belgium tonight is a mystery for the ages. They were far, far better than Genk, with Adil Rami hitting the crossbar, Ever Banega and Roberto Soldano torturing` keeper Laszlo Koteles all night long, and Dani Parejo missing a sitter. No score, no blood, and a lot of questions for manager Unai Emery: Valencia look to be a team that may be more hype than reality.

Plzen and BATE Borisov deservedly shared the points in their match of rank outsiders. Marek Bakos was alone at the far post in first half injury time to finish from Petr Jiracek and put Plzen ahead, but the visitors never became defensive, kept the pressure on and got their point when Dmitri Baga sent in Renan Bressan for the Brazilian to tie things up.