Aston Villa 2 Ajax 1: Aston Villa got their Uefa Cup campaign of to winning start at home to Ajax but Portsmouth were knocked out of their stride by FC Braga in Portugal as they lost early ground to group opponents AC Milan.
At Villa Park, Martin O'Neill's side faced former European champions Ajax but showed no signs of stage fright with Martin Laursen heading home from a corner for an early lead.
Vermaelen headed an equaliser from an Ajax corner 20 minutes later but club captain Gareth Barry struck the eventual winner with a controlled effort from the edge of the box on the stroke of halftime.
The result sees Villa move top of Group F with Hamburg after Martin Jol's side earlier beat MSK Zilina 2-1 away.
It wasn't all good news for Villa, however, after Gabriel Agbonlahor collided with the Ajax goalkeeper late on and received lengthy treatment before being replaced by Curtis Davies.
Portsmouthwere well beaten on their return to Portugal as goals by Luis Aguiar, Wason Renteria and Alan secured a convincing win for Sporting Braga.
With AC Milan next up for Portsmouth in the group stages, this was not the way Harry Redknapp wanted his team to start their Group E campaign.
Portsmouth went behind when Aguiar hit a stunning 30-yard strike in the eighth minute, and Jermain Defoe missed the only clear chance for the Premier League side. Glen Little and Armand Traore limped off injured to add to the visitors' woes.
AC Milangot their Group E adventure off to the best possible start with a comfortable 3-1 win over Dutch side
Heerenveen.
An own goal from Heerenveen midfielder Calvin Jong-a-Pin after 19 minutes set Milan on their way before goals from Gennaro Gattuso and Filippo Inzaghi put the Italians out of sight.
Danijel Pranjic added a late consolation goal for the hosts from the penalty spot.
Romano Denneboom scored the only goal as
FC Twenteclinched a home victory against
Racing Santander.
The Dutch striker latched onto Kenneth Perez's cross in the fifth minute to give the Eredivisie side all three points in their first Group A clash at the Grolsch Veste stadium.
Galatasaraygot their Group B campaign off to a winning start with a narrow 1-0 victory over
Olympiacosin a closely-contested clash in Istanbul.
Harry Kewell's glancing header was enough to give Michael Skibbe's Turkish champions all three points.
Hertha Berlinfought back to register a hard-earned point in a 1-1 draw against
Benficain Group B. The Portuguese champions went ahead after 51 minutes through Angel di Maria but Hertha equalised 16 minutes from time through Marko Pantelic.
Sevillabegan their campaign with a 2-0 win over
Stuttgartin Group C.
Goals from Romaric and Renato Dirnei in the 15th and 16th minutes were enough to set the 2006 and 2007 champions on their way to the three point.
St Etiennecelebrated their return to European action after a 26-year absence by beating
FC Copenhagen3-1 in Group G .
In a dramatic opening, Morten Nordstrand missed a penalty for the hosts just a minute after Bafetimbi Gomis had put St Etienne in front.
Loic Perrin added a second for the visitors in the 37th minute and, though Cesar Santin's penalty reduced the arrears just before the hour, Dimitri Payet's strike sealed the win for the French side.
Nancystruck three second-half goals to down
Feyenoordin Group H.
Nancy entered the game low on confidence having managed just one win in nine Ligue 1 games to start the season and they were second best for the majority of the opening half as Feyenoord piled on the pressure.
But the visitors failed to find the net and were made to pay when first Julien Feret and then Monsef Zerka struck inside eight minutes of the restart.
Maurilio Helder added a third after 84 minutes.
Sampdoriarecorded a 2-1 victory at
Partizan Belgradein Group C.
Partizan's Lamine Diarra had cancelled out Emiliano Bonazzoli's opener for Samp but Daniele Dessena's second-half strike gave the visitors a vital win.
In Group G,
Rosenborgwere held to a disappointing home draw against Belgian outfit
Club Brugge.
