Rather than following the lead of Mohamed Salah and Virgil van Dijk, who have signed new two-year contracts to remain at Anfield, Alexander-Arnold is expected to leave Liverpool at the end of the season.

The England full back has won almost every trophy available to him since making his Liverpool debut in 2016, lifting the UEFA Champions League, Premier League, FA Cup, Carabao Cup, FA Community Shield, UEFA Super Cup and FIFA Club World Cup trophies.

He struck the winner in a 1-0 victory over Leicester City on Monday (AEST) to put the Reds on the brink of a second Premier League triumph.

Despite that goal, Alexander-Arnold has been criticised by many Liverpool fans for his failure to commit his future to the club, while Jamie Carragher said after the Leicester win that Arne Slot should bench the full back if he is on his way out.

But Kewell, who won the FA Cup and UEFA Champions League with Liverpool, does not begrudge Alexander-Arnold his next move.

"I'm probably not going to win a lot of fans with this, but I think Trent has done amazing things at Liverpool," he said.

"To virtually win everything possible ... that's phenomenal. If he now wants a new challenge, if that's the path he chooses, then fair play to him.

"Liverpool are one of the biggest clubs in the world, but he's not going to a smaller club; he's going to Real Madrid. That's a club with just as much expectations.

"The pressure there will be huge, but he's used to that. The pressure of playing at Anfield is massive. I remember when I played, opponents used to dread coming to Anfield. They'd be like, 'Oh my God, the pressure is too much'.

"He's lived that. He's earned the right to choose his next step. I understand the frustration from fans, but he's achieved everything with Liverpool.

"He's allowed to think about his own path now. If that means going abroad to challenge himself again, so be it. He's earned that right."

Alexander-Arnold's left-footed volley was his 23rd goal for Liverpool, but the first not to be scored with his right foot.

Since making his Premier League debut in December 2016, Alexander Arnold has more assists (64) and total goal involvements (82) than any other defender in the competition, also leading the way for chances created (514).

"We all know what he's capable of; his passing range is phenomenal. I've said it before: he's probably one of the best crossers we've ever seen in the Premier League," Kewell added.

"There's a trade-off. Defensively, he's not a natural defender, but what he gives you in attack is outstanding.

"He's been able to do that in part because he's had someone like Van Dijk behind him – arguably the best defender the Premier League has seen. That gives him the freedom to push forward and influence games."