Arsenal were held to a 1-1 draw by relegation-threatened Portsmouth on Wednesday as their hopes of finishing fourth in the English Premier League suffered a blow.
The result left the European Cup semi-finalists four points behind north London rivals Tottenham Hotspur in the race for the final qualifying spot in next season's Champions League.
Arsenal moved up a place to fifth, above Blackburn Rovers on goal difference, while Portsmouth stayed in the bottom three but climbed one spot to 18th level on points with Birmingham City.
Thierry Henry put Arsenal ahead after 36 minutes with a precise shot into the far corner but Lomana LuaLua equalised for Portsmouth in the 66th with a powerful header.
Arsenal striker Emmanuel Adebayor squandered two clear chances to put Arsenal further ahead before LuaLua's leveller but he contrived to miss with a shot and a header.
"Given the chances we created and the chances they had it was a disappointing result for us," Arsenal manager Arsene Wenger told Sky Sports.
The Londoners made several changes after a 2-0 loss at Manchester United on Sunday, fielding a young central midfield partnership of Abou Diaby and Alex Song.
However, Wenger refused to blame his team selection, saying: "I don't think we dropped the points tonight because of that."
Henry got Arsenal off to the perfect start as he showed his class with a fine goal from outside the box after dispossessing Sean Davis and playing a neat one-two with Adebayor.
The Togo forward should have got their second himself five minutes later when Henry returned the compliment with a pass that set him up in front of goal but Adebayor fluffed his shot.
CAMPBELL RETURNS
Arsenal's Sol Campbell, playing for the first since storming out of Highbury on February 1, had to be treated for a cut eye after an accidental elbow by Benjani Mwaruwari just after the break.
Campbell was the first Englishman to play for Arsenal since his last appearance 13 games ago when he was substituted at halftime after a poor display in a 3-2 loss to West Ham United.
He was given compassionate leave after that match and then suffered ankle and toe injuries but the England hopeful managed a solid display on Wednesday on his return to the first team.
Adebayor missed another sitter just before the hour when he flashed a header wide from point-blank range after being left unmarked in front of goal at a corner.
Arsenal were made to pay for Adebayor's profligacy after 66 minutes when LuaLua headed powerfully past Jens Lehmann from a free kick on the right by midfielder Andres D'Alessandro.
Campbell, already bloodied by his cut eye, then received a bang on the nose as he challenged for a header and came off just before the end with blood streaming down his face.
"He coped very well," said Wenger. "He dipped a little bit in the second half but it was more down to the injury he got."
The visitors pressed for the winner in the closing stages but could not find a way past Dean Kiely in the Portsmouth goal and had to settle for a draw in the re-arranged match.
"It was a great point," said delighted Portsmouth manager Harry Redknapp. "To go behind to Arsenal and come back and take a point was a great performance. We deserved it in the end."
After 33 games Spurs have 58 points while Arsenal are level on 54 with Blackburn. Portsmouth now have 29 points alongside Birmingham with both teams a point above West Bromwich Albion.
