Inter Milan got off to an unconvincing start in defence of their UEFA Champions League title as they drew away with FC Twente 2-2 on Tuesday, while Barcelona displayed amazing form to thrash Panathinaikos 5-1.

Wesley Sneijder, booed by some home fans on his return to the Netherlands, put the visiting Inter ahead after 13 minutes when he slotted home after Diego Milito's shot had been parried.

The Dutch champions soon hit back with an unstoppable Theo Janssen free kick before Milito, enduring a difficult start to the season having been inspirational last term, glanced in an own goal from a corner.

Diego Milito of Inter Milan (L) scores an own goal against Twente Enschede next to his teammate Lucio (2nd L) during their Champions League Group A soccer match in Enschede September 14, 2010.

Inter reacted quickly to going behind in the downpour and the slick surface helped Samuel Eto'o fire in a superb equaliser from outside the area after 41 minutes following Goran Pandev's layoff.

Inter have looked off the pace this term with new coach Rafael Benitez, frustrated at the club not strengthening in the transfer window, coming under immediate pressure following the stunning treble success of Jose Mourinho last season.

A Lionel Messi-inspired Barcelona recovered from the shock of going a goal down against Panathinaikos to get their Champions League campaign off to a convincing start at Camp Nou with an overwhelming victory.

Panathinaikos took the lead against the run of play through Sidney Govou in the 20th minute but Barca hit back in merciless fashion to take a 3-1 lead by half-time through two goals from the irrepressible Messi and another from David Villa.

Messi, having also hit the crossbar in the first half, spurned the chance to net his hat-trick in the 55th minute when his weak penalty was saved by Alexandros Tzorvas, but teed up Pedro and Daniel Alves for further goals.

A weakened Manchester United team could only draw 0-0 with Rangers in their opening Champions League tie as Antonio Valencia suffered what appeared to be a serious injury.

United made ten changes from the side that drew with Everton at the weekend and failed to carve out enough chances at Old Trafford when being frustrated with a defensive Rangers side.

Barcelona's David Villa (R) celebrates with teammate Lionel Messi after scoring against Panathinaikos during their Champions League Group D soccer match at Nou Camp stadium in Barcelona September 14, 2010.

Midfielder Valencia was taken to hospital after suffering what appeared to be a broken leg in the second half following a challenge from Kirk Broadfoot. The Ecuadorian required oxygen on the pitch when he was carried off the pitch.

Tottenham's first ever Champions League game started superbly when an own goal from Petri Pasanen and a towering header from Peter Crouch put them 2-0 up against Bremen, but they were held to a 2-2 draw in Bremen.

The German side responded in four second-half minutes as Hugo Almeida and the excellent Marko Marin drew the hosts level. Almedia scored with a header after 43 minutes and Marin fired home a low effort soon after.

Benfica put their poor domestic form to one side as they opened their Champions League Group B campaign with a comfortable 2-0 win at home to Hapoel Tel Aviv.

Jorge Jesus' Portuguese champions have lost three of the opening four matches in the Liga but were on course when their Brazil defender Luisao scored after 21 minutes. Oscar Cardozo then added a second after 69 minutes to seal the points against a Hapoel side making their first appearance in the group stage.

Valencia started their Champions League Group C campaign with a thumping 4-0 away win in Turkey against Bursaspor.

Bursaspor beat Istanbul giants Galatasaray, Besiktas and Fenerbahce to win their domestic title last season but had no answer against the Spanish Primera Division side. Facundo Costa and Aritz Aduriz scored in the first half and Pablo Hernandez and substitute Roberto Soldado added a deserved coat of gloss after the interval.

Barcelona's Lionel Messi gestures as he celebrates after scoring his second goal against Panathinaikos during their Champions League Group D soccer match at Nou Camp stadium in Barcelona September 14, 2010.

Inter Milan got off to an unconvincing start in defence of their UEFA Champions League title as they drew away with FC Twente 2-2 on Tuesday, while Barcelona displayed amazing form to thrash Panathinaikos 5-1.

Wesley Sneijder, booed by some home fans on his return to the Netherlands, put the visiting Inter ahead after 13 minutes when he slotted home after Diego Milito's shot had been parried.

The Dutch champions soon hit back with an unstoppable Theo Janssen free kick before Milito, enduring a difficult start to the season having been inspirational last term, glanced in an own goal from a corner.

Diego Milito of Inter Milan (L) scores an own goal against Twente Enschede next to his teammate Lucio (2nd L) during their Champions League Group A soccer match in Enschede September 14, 2010.

Inter reacted quickly to going behind in the downpour and the slick surface helped Samuel Eto'o fire in a superb equaliser from outside the area after 41 minutes following Goran Pandev's layoff.

Inter have looked off the pace this term with new coach Rafael Benitez, frustrated at the club not strengthening in the transfer window, coming under immediate pressure following the stunning treble success of Jose Mourinho last season.

A Lionel Messi-inspired Barcelona recovered from the shock of going a goal down against Panathinaikos to get their Champions League campaign off to a convincing start at Camp Nou with an overwhelming victory.

Panathinaikos took the lead against the run of play through Sidney Govou in the 20th minute but Barca hit back in merciless fashion to take a 3-1 lead by half-time through two goals from the irrepressible Messi and another from David Villa.

Messi, having also hit the crossbar in the first half, spurned the chance to net his hat-trick in the 55th minute when his weak penalty was saved by Alexandros Tzorvas, but teed up Pedro and Daniel Alves for further goals.

A weakened Manchester United team could only draw 0-0 with Rangers in their opening Champions League tie as Antonio Valencia suffered what appeared to be a serious injury.

United made ten changes from the side that drew with Everton at the weekend and failed to carve out enough chances at Old Trafford when being frustrated with a defensive Rangers side.

Barcelona's David Villa (R) celebrates with teammate Lionel Messi after scoring against Panathinaikos during their Champions League Group D soccer match at Nou Camp stadium in Barcelona September 14, 2010.

Midfielder Valencia was taken to hospital after suffering what appeared to be a broken leg in the second half following a challenge from Kirk Broadfoot. The Ecuadorian required oxygen on the pitch when he was carried off the pitch.

Tottenham's first ever Champions League game started superbly when an own goal from Petri Pasanen and a towering header from Peter Crouch put them 2-0 up against Bremen, but they were held to a 2-2 draw in Bremen.

The German side responded in four second-half minutes as Hugo Almeida and the excellent Marko Marin drew the hosts level. Almedia scored with a header after 43 minutes and Marin fired home a low effort soon after.

Benfica put their poor domestic form to one side as they opened their Champions League Group B campaign with a comfortable 2-0 win at home to Hapoel Tel Aviv.

Jorge Jesus' Portuguese champions have lost three of the opening four matches in the Liga but were on course when their Brazil defender Luisao scored after 21 minutes. Oscar Cardozo then added a second after 69 minutes to seal the points against a Hapoel side making their first appearance in the group stage.

Valencia started their Champions League Group C campaign with a thumping 4-0 away win in Turkey against Bursaspor.

Bursaspor beat Istanbul giants Galatasaray, Besiktas and Fenerbahce to win their domestic title last season but had no answer against the Spanish Primera Division side. Facundo Costa and Aritz Aduriz scored in the first half and Pablo Hernandez and substitute Roberto Soldado added a deserved coat of gloss after the interval.

Barcelona's Lionel Messi gestures as he celebrates after scoring his second goal against Panathinaikos during their Champions League Group D soccer match at Nou Camp stadium in Barcelona September 14, 2010.