Wrexham striker Paul Mullin suffered a punctured lung during a 3-1 pre-season win over Manchester United on Tuesday, when he collided with the opposition goalkeeper in the pre-season friendly in San Diego, California, manager Phil Parkinson said.

Mullin, who was Wrexham’s leading scorer last season with 46 goals in all competitions, collided with United’s Nathan Bishop when the goalkeeper rushed out to stop a long ball.

Mullin stayed down and was attended to by physios who gave him oxygen while a stretcher was also brought out. However, the 28-year-old was able to walk off the pitch before he was replaced.

Parkinson said he was left “fuming” after the goalkeeper received only a yellow card for the challenge and revealed Mullin had been shifted to the hospital. “It was a reckless, challenge in a pre-season game and I’m not happy with it at all. I haven’t seen the goalie and he’s probably best steering clear of us for the time being because we’re not very happy,” he said after the game. “It should have been a straight red.”

Mullin later posted a message on Instagram saying: “Thank you for all your messages! All good here!”.

Bishop later posted an apology on social media, wishing Mullin the “speediest recovery”.

“A misjudgement and a genuine accident with zero malicious intent,” he said.