Hamburg  - There is all to play for in the Champions League after Tuesday night's first round matches in the round the last 16 failed to produce any clear winners.

Inter Milan were held to a goalless draw by Manchester United in Italy, Barcelona played to a 1-1 draw at Olympique Lyon and former winners Porto drew 2-2 in Madrid against Atletico.

The only victory on the night belonged to Arsenal who missed a number of excellent chances against AS Roma, but still registered a 1-0 victory through Robin van Persie's first half penalty.

In Lyon the home side started like a house on fire with Brazilian midfielder Juninho, who is widely considered as the best dead-ball specialist in the world, curling a free-kick over Barcelona goalkeeper Victor Valdes for the opening goal in the 7th minute.

Just two minutes later French international Karim Benzema should have doubled his side's lead after being sent through but he pulled his ball just wide.

Barcelona then came back into the game and top scorer Samuel Eto'o was unlucky not to equalize for the visitors as his 15th minute strike crashed against the upright and bounced back into play.

In the second half Barcelona pressed to level matters and their efforts paid off in the 65th minute when Thierry Henry stole his way past his marker and headed home from close range.

Dutch striker van Persie proved to be Arsenal's match-winner as he earned the Gunners a 36th minute penalty, from which he scored himself.

The Londeners had several other good opportunities but Danish striker Nicklas Bendtner and Emmanuel Eboue failed to make the most of good chances.

In Milan the much-anticipated match-up between Jose Mourinho's Inter Milan and Sir Alex Ferguson's Manchester United failed to live up to its top-match billing.

The Serie A side surprisingly played a defensive game and allowed United most of the possession but they, in turn, failed to make the most of their chances, with Ronaldo and Ryan Giggs coming close, but failing to beat Inter goalkeeper Julio Cesar.

Argentine striker Lisandro Lopez scored twice in Madrid for former Champions League winners Porto to give his side the advantage ahead of the return leg after a 2-2 draw against Atletico Madrid.

Maxi Rodriguez opened the scoring for the home side in the 3rd minute after being set up by Diego Maradona's son-in-law Sergio Aguero.

Lisandro equalized for Porto midway through the first half, but Porto's goalkeeper Helton gifted the home side another goal two minutes into first half injury time as he let a speculative Diego Forlan shot slip through his hands.

Lisandro managed to get his sixth Champions League goal of the season in the 72nd minute when he latched onto a pass from French defender Aly Cissokho to give Porto a deserved share of the spoils.

The return legs are to be played March 10 and 11. (dpa)