AC Milan held Barcelona to an entertaining 0-0 draw on Wednesday in the opening leg of the quarterfinals, the first time in 30 matches and more than two years that the Spanish team had been held scoreless in the Champions League.
The last time Barcelona failed to score in the Champions League was in the 0-0 draw with Rubin Kazan in November 2009.
Milan will find out in the return leg at the Camp Nou next Tuesday how much it will regret Robinho's woeful miss early on, while Barcelona should've had a first-half penalty when Alexis Sanchez was brought down by goalkeeper Christian Abbiati.
Lionel Messi, who has scored 55 times this season, had a goal rightly ruled out for offside at the San Siro.
This is only the second time a match between these two European heavyweights has ended scoreless in 14 meetings.
Zlatan Ibrahimovic, who spent an unhappy season at Barcelona, was also kept quiet although he should have done better with two opportunities.
These teams played each other in the group stage, with defending champion Barcelona beating Milan 3-2 in November in their last matchup. And the opening stages of this game appeared to promise a similar amount of goals.
Madrid forward Robinho should have scored in the third minute.
Milan attacker Kevin Prince Boateng's shot crashed off defender Gerard Pique and the rebound was headed on by Ibrahimovic to an unmarked Robinho just outside the six-yard box, however the Brazilian shot over the crossbar.
Milan was almost made to rue that missed opportunity immediately, Messi drilling the ball low across the face of goal.
Barcelona went close when Abbiati spilled Messi's shot but Antonio Nocerino managed to clear off the line with Dani Alves sliding to try and tap it into the net in the ninth minute.
The Spanish side should have had a penalty after a well-worked free kick came to Sanchez, who beat the offside trap, rode a tackle from behind and was then brought down by Abbiati as he rounded the goalkeeper.
Seconds later, Messi slotted home from Alves' cross, only to be adjudged offside.
Ibrahimovic had his first sight of goal in the 20th minute, shooting straight at goalkeeper Victor Valdes. But Barca was starting to get into its stride to dominate possession as Milan struggled to carve out opportunities.
A lovely Barca move followed by a one-two between Xavi and Messi finished with the midfielder's shot being parried by Abbiati.
Milan was leaving itself dangerously exposed at times at the back, and was almost caught out when Sanchez raced half the length of the pitch with Luca Antonini in pursuit. The Milan defender managed to get in a last-ditch tackle in the middle of the box as the striker was about to shoot.
Ibrahimovic could have put Milan ahead when he was picked out in a dangerous position by Massimo Ambrosini in the 57th, but the Sweden striker failed to control the ball and Barca cleared the danger.
As the match lost some of its frenetic pace, Barcelona defender Carles Puyol went close with a glancing header from a corner that only just went the wrong side of the post.
Barcelona could have won the match three minutes from time but Abbiati brilliantly stopped Messi's fierce effort, before Antonini cleaned up the rebound to clear the danger.
Messi felt aggrieved not to have been granted a penalty when he was muscled off the ball and brought down by two Milan defenders, but the initial contact looked to have been outside the box.
