Arsenal manager Unai Emery says Hector Bellerin is mature enough to recover from his latest injury set back and come back a stronger player.
It was revealed on Tuesday that the 23-year-old will be ruled out for up to nine months after rupturing his anterior cruciate ligament against Chelsea last weekend.
Bellerin had only just recovered from a calf strain that had kept him out of action over the festive period, but he is now set to miss the rest of the 2018-19 season at least.
Speaking to the Gunners' official website , Emery said: "Yes, we were sad and we are sad now after his injury. I think this year is very difficult for big injuries like Hector, Rob Holding and [Danny] Welbeck.
"But football is like that. We need to treat these injuries like a normality in football, but we are very sad for that.
"Hector Bellerin is very mature and I think he received this injury like a football professional can take and he is already preparing to come back stronger than before."
The right-back was stretchered off in the 70th minute at the Emirates Stadium as Arsenal cruised to a 2-0 win during a crucial game in the race to qualify for next year's Champions League.
Both Holding and Welbeck are expected to miss the remainder of the campaign as well, and Emery admitted his side is in need of new recruits this month.
Chelsea currently occupy fourth spot in England's top flight, with both Arsenal and the Red Devils trailing by just three points after United have bridged an eight point gap to the Gunners since Ole Gunnar Solskjaer took over.
Emery's side will take on United for the first time since Solskjaer's appointment as interim boss when the two teams clash in the FA Cup fourth round at the Emirates Stadium this Friday.
There are few obvious replacements for Bellerin in that game, but Nacho Monreal or Ainsley Maitland-Niles could deputise.