Manchester United manager Louis van Gaal was frustrated after his side were held to a 1-1 Old Trafford draw thanks to a deflected late Arsenal equaliser.
United were in front at the break thanks to a controlled low finish by Ander Herrera, with the visitors failing to muster much threat as the hosts dominated.
But as the clock ticked into the last 10 minutes, Theo Walcott's cross flew off Tyler Blackett's leg and past substitute goalkeeper Victor Valdes, on for the injured David De Gea.
Both De Gea and striker Radamel Falcao waved to the fans as they were substituted, sparking speculation that neither will be a United player when next season begins.
The BBC quoted Van Gaal -- whose side are now almost certain to finish fourth with the Gunners in third place -- as saying: "You can say we are unlucky because it is the third deflected goal in a row and goes in our net.
#INSERT type:image caption:Ander Herrera's strike had put United ahead at Old Trafford. END#
"But I have said to the players it is not unlucky. You have to force luck by finishing games. We were 1-0 ahead. You see Arsenal want to come back, so you have to stick together and be compact.
"I have said Arsenal have maybe the best team but Chelsea can finish the game, which Arsenal cannot do -- and we can't either.
"That is important. This season, we have only finished two games. It is a pity."
If United finish fourth they will have to play a qualifying round for the Champions League, and Van Gaal warned: "It is always stressful as you can meet opponent who is halfway through a season already. It is not so easy.
"But I want more as manager. Next year, we will fight for more."
He said De Gea's future remained to be decided, despite repeated reports linking him with a move to Real Madrid.
"It is a process for David De Gea," he said. "He will not leave us easily as we have a great club and he wants to participate.
"But he is Spanish, and he could go to a great club. It is difficult for him to decide."