LONDON • Unai Emery bizarrely insisted Shkodran Mustafi "has been consistent all season" after his abject display against Crystal Palace ensured the top-four race remained wide open.
The Germany defender was culpable for all three goals as Arsenal were shocked 3-2 in the Premier League at home on Sunday.
It ended their 10-game winning streak at the Emirates Stadium, where they had six clean sheets in seven games in all competitions.
The 27-year-old abandoned marking duties to allow Christian Benteke to nod in his first goal of the season and his first in a year, before switching off to give Wilfried Zaha a free run on goal as he placed his shot past Bernd Leno.
Sandwiched in between was Mesut Ozil's equaliser, but Mustafi was again to blame after losing James McArthur, who headed home from a corner. Pierre-Emerick Aubameyang netted the hosts' second goal.
But afterwards, Arsenal boss Emery still felt Mustafi, who started as Sokratis Papastathopoulos was serving out his two-match ban, could "play very well".
The Spaniard said: "We are, every player, helping, playing with a big performance. Against Benteke and Zaha, you can suffer more. If today, we were better in the set pieces, maybe we could win this match."
Palace got their first league win at Arsenal since October 1994, while the Gunners' first home league defeat since the season-opening setback against Manchester City has dented their hopes of reaching the Champions League.
But Emery is still convinced they can finish in the top four, even though their next two games will be testing encounters at Wolves tomorrow and Leicester on Sunday.
He said: "We still have the possibility to achieve our first target... through the league or Europa League.
"In this key moment, we have the chance to fight for the top four. If we win at Wolverhampton, it is still in our hands."
Pundits and fans alike were, however, less optimistic about Arsenal improving their dismal away record, with six of their eight losses coming on the road this season, especially with Mustafi in the team.
Former Gunners defender Martin Keown blasted the schoolboy defending, telling BBC Sport that "his poor decision-making is costing his team". TV personality Piers Morgan was even more scathing, tweeting that he was the "biggest waste of £35 million (S$61.7 million transfer fee paid to Valencia) in world football history".