London (AFP) - Arsenal's chances of finishing in the top four of the Premier League suffered another setback with a 2-1 loss at home to Brighton on Saturday.
Brighton's Enock Mwepu created a first-half opening goal at the Emirates for Leandro Trossard before doubling the lead in the 66th minute.
Martin Odegaard pulled a goal back in the 89th minute with a long-range strike but his effort could not prevent the Gunners suffering a third defeat in four league games.
Arsenal remain in fifth place, level on points with fourth-placed Tottenham who are in action later Saturday against Aston Villa.
"It has been a tough week; especially today because we wanted a reaction (to the defeat at Crystal Palace)," Arsenal manager Mikel Arteta told the BBC.
"We made it really difficult for ourselves.We were sloppy, we had no purpose to attack, we were really imprecise and we didn't want to play forward.
"There are many games to play but we have to be concerned about that performance, especially first half."
Brighton's fourth win in 26 league games saw the Seagulls climb into 11th place in the table.
"It is a fantastic performance from the players and an even better result; I'm delighted for them," said Brighton boss Graham Potter.
"We had to hang on and suffer, but we did and the result makes it worth it.You have to disciplined and good defensively here; (Arsenal) are a team who are competing for the Champions League places."
Following fine work by Mwepu, the visitors went ahead through Trossard's curling shot shortly before the half-hour mark.
Gabriel Martinelli appeared to have headed Arsenal level on the brink of half-time, but after an agonising four-minute VAR check, his effort was disallowed for offside.
Brighton remained solid at the back before Zambia midfielder Mwepu doubled their lead with a powerful side-footed finish from the edge of the box to the disbelief of Arteta.
Odegaard gave Arsenal hope of a share of the spoils with a deflected shot but Brighton saw the game out.
