Glasgow, Scotland (My Sportsbook) - William Gallas directed the first goal in off his back and Gary Caldwell added an own goal, helping Arsenal to a big 2-0 win over Celtic in a first leg Champions League playoff game Tuesday at Celtic Park.

Gallas tried to duck out of the way of a shot from Cesc Fabregas in the 43rd, but the ball deflected off his back from about 15 yards out and bounced inside the right post. Caldwell, Celtic's captain, sealed Arsenal's win when he sent a cross from Gael Clichy into his own net in the 71st.

Arsenal, which opened the English Premier League season with a 6-1 win against Everton over the weekend, takes two big away goals back to London. The Gunners host Celtic on Aug. 26 in the second leg with a group stage spot on the line.

Stuttgart opened with a 2-0 win on the road over Timisoara, as did Olympiacos with a 2-0 win at Sheriff. FC Copenhagen opened with a 1-0 home win over APOEL and Fiorentina earned a 2-2 draw at Sporting Lisbon.

Arsenal broke the deadlock two minutes before half off a free kick. Fabregas drilled the ball toward the left post - which Celtic goalie Artur Boruc seemed have covered - but Gallas wandered into the area and, as he tried to duck to let the ball go on net, was hit in the back and the ball sailed perfectly into the right side.

Denilson and Robin Van Persie had chances in the first 10 minutes after half, but it wasn't until the 71st that Arsenal grabbed the two-goal edge on another lucky bounce.

Clichy drove down the left side and tried to send a cross through the area to the far post. Caldwell slid in to try and knock the ball wide for a corner but directed it past Boruc for an own goal.

Stuttgart scored both of its goals in a four-minute stretch of the first half to beat Timisoara. Timo Gebhart converted a penalty in the 27th, and Alexander Hleb added the second goal in the 30th.

Alexandro Dudu and Kostas Mitroglou scored after half to lead Olympiacos over Sheriff, Zdenek Pospech scored in the second half to lead FC Copenhagen over APOEL, and Alberto Gilardino scored in the 79th as Fiorentina rallied to earn a tie at 10-man Sporting.

On Wednesday the Champions League playoff first legs continue with Anderlecht visiting Lyon, Atletico Madrid visiting Panathinaikos, Debrecen visiting Levski Sofia, Maccabi Haifa visiting Red Bull Salzburg, and Zurich visiting Ventspils.