The defender is out for the season due to a knee setback.
O'Neil said, “He's a great kid, so I’m absolutely devastated for him because of his energy and his life. No matter how things go each week, he gives absolutely everything, and he always attacks things and does things in the right way. A big loss to us from that point of view. He was showing signs that he was capable of playing at the level we were hoping.
“So, from a team and a squad point of view, a big blow to us, obviously, but with that brings opportunity for others. Alfie Pond, for instance, gets a step closer. A boy that was obviously out on loan last year at Stockport, played for us in the cup at Brighton, and is extremely excited this week that he’s around it and there’s a chance of featuring in Premier League games.
“I am absolutely gutted for Yerson, and it's a blow to the group and where we are, but we have a real good mentality inside the place that we don't let things like that stop what we're trying to do and what we're trying to be. We’re always going to suffer setbacks in a Premier League season, this is a big one, especially for Yerson personally, but we will find a way to make sure that we’re still capable of fighting and picking up points.”