
Ronald Araujo played in Bradley Barcola down the right, and his cross bounced off Gross into the path of Wirtz. Liverpool's number seven rifled the ball into the back of the net, but it took a huge deflection off his fellow German, leaving Bart Verbruggen with no chance of saving the shot.
Wirtz was bright throughout the afternoon, but picked up a knock in the second half and had to be replaced. He looked uncomfortable after coming together with Yasin Ayari just after the hour mark and was replaced by youngster Trey Nyoni.
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The German international went straight down the tunnel after shaking hands with Andoni Iraola, and Sky Sports commentator Vinny O'Connor said: "Wirtz didn't look comfortable after what looked to be an ankle knock and went straight down the tunnel.
"It's a shame because there was so much good about his performance and work-rate this afternoon."
Speaking after the win over Brighton, Iraola gave an update on Wirtz's injury and said: "Unfortunately, he had to leave the pitch with a small twist of the ankle.
"It doesn't look very big, but we are playing every three days, so we need to see where he is."
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There was some concern that Liverpool may be forced into another quick change, with Wirtz's replacement Nyoni also seen limping just minutes after coming on. However, the youngster shook off the knock and was able to help Liverpool get the result over the line.
The win takes Liverpool up to fourth, just one point behind the Seagulls with the Reds winning four games in a row in all competitions.
It was the Reds first win on home soil in the league this season after draws with Nottingham Forest and Fulham, with Man City running out 3-0 winners last weekend.
Iraola's side are six points behind Premier League leaders Manchester City, while Arsenal are in second just behind Enzo Maresca's men on goal difference.