Manchester, England:Five-time winner Liverpool lost at Fiorentina in the Champions League on Tuesday, while defending champion Barcelona won its first game and Inter Milan was held to a second successive draw.
Teenage Fiorentina forward Stevan Jovetic scored twice in a 2-0 win over the Reds to sit second in Group E behind Lyon, which thrashed Debrecen 4-0.
"Everyone is disappointed, but at this level every team is a good team," Liverpool manager Rafa Benitez said. "We were not the best in any part of the pitch. We knew that they were a good team - very organized, good on the counterattack - and we were giving the ball away all the time and giving them chances."
Lionel Messi and Pedro Rodriguez scored to give Barcelona a 2-0 victory over Dynamo Kiev to go top of Group F, as Inter drew 1-1 at Rubin Kazan.
Arsenal relied on late goals from Robin van Persie and Andrei Arshavin to beat Olympakios 2-0 and stay perfect in Group H. Standard Liege drew 1-1 with AZ Alkmaar in the other group match.
Sevilla moved four points clear at the top of Group G after thrashing Rangers 4-1, while Stuggart could only draw 1-1 at Unirea.
At the Camp Nou, Messi scored in the 26th minute when he received Andres Iniesta's pass and cut in from the right before delivering a powerful low shot that goalkeeper Olexandr Shovkovskiy couldn't keep out.
Substitute Pedro doubled Barcelona's lead in the 76th with a low left-footed shot from Zlatan Ibrahimovic's pass.
"It's an important win," Pedro said. "It's always important to win your home matches in the Champions League."
Kiev included Andriy Shevchenko on his 33rd birthday despite a doubt over an eye injury. The striker scored a hat trick at Camp Nou in Kiev's 4-0 win in the competition 12 years ago, but there was to be no repeat.
Inter, which drew with Barca in the Group F opener, is still winless but the Italians were fortunate to leave Russia with a draw.
Alejandro Dominguez gave Rubin Kazan the lead in the 11th minute, firing high into the net after beating Inter center back Lucio with a stepover.
Inter midfielder Dejan Stankovic headed the equalizer in the 27th minute.
"Considering the circumstances of the game, it's a point earned," Inter coach Jose Mourinho said. "Obviously we want to advance as early as possible. We drew in a game that, considering the circumstances, we could have lost."
Inter had to play the last 30 minutes with 10 men after teenage forward Mario Balotelli was sent off for a second bookable offense after fouling Rubin's Christian Nobao.
Another teenager was the star of the night in Florence, where the 19-year-old Jovetic scored twice in the first half against Liverpool.
Jovetic took a pass from Cristiano Zanetti and slid the ball past goalkeeper Pepe Reina in the 28th, then redirected in a shot from Juan Vargas nine minutes later.
Fiorentina and Liverpool are tied in Group E with three points each.
Lyon, which leads with a perfect six points, scored its first goal in the third minute against Debrecen when Swedish international Kim Kallstrom expertly controlled a corner and volleyed home.
Miralem Pjanic scored from a free kick in the 13th, Sidney Govou made it 3-0 in the 24th and Bafetimbi Gomis completed the rout in the in the 51st.
In Glasgow, Abdoulay Konko's 50th-minute header sparked a second-half goal spree as Sevilla thrashed Rangers in Group G.
The 25-year-old Konko, making his competition debut, headed in Jesus Navas' free kick to break a 0-0 deadlock.
Rangers' players were earlier angered because they felt a penalty should have been awarded against Konko in the first half for fouling Steven Naismith.
But Sevilla ran rampant after Konko's opener, with Adriano, Luis Fabiano and Fredi Kanoute also scoring.
Nacho Novo scored a late consolation goal for Rangers. The Scottish champions are bottom with one point after two matches.
In the other Group G match, Stuttgart was ahead in the fifth minute against Unirea through defender Serdar Tasci's goal.
Unirea equalized three minutes into the second half when forward Dacian Varga curled the ball into the far corner.