Liverpool boss Jurgen Klopp admits the progress of Trent Alexander-Arnold has surprised him and his staff.

Klopp remembers being tipped off about the gangly teenager by his assistant Pep Lijnders and never dreamed he would go on to become one of the finest right backs in the world.

Now 23, Alexander-Arnold's quick recovery from a hamstring injury to face Manchester City is a huge boost for Liverpool.

"He developed in a way nobody could have expected," says Klopp. "He had a great mentor in Pep who coached him at the Under 16s. Pep started to tell me about this boy, then this skinny kid came around the corner. You could see he was special but there was a lot of work to do, especially physically.

"Look at the first pictures of Trent when he scored his first goal against Hoffenheim (in 2017) and the man he became now. Wow, what a difference.

"Whatever you set up as a coach, 80 or 90 per cent is up to the player. If you give a player freedom and there is no output, all you do is open your formation and get exposed. So yeah, he did well so far!"

Alexander-Arnold has redefined the full back position and has a personal-best 16 assists this season. Klopp believes the role could develop even further over time.

"You don't tell a full back from the first day to play really higher all the time. You develop as a team. We can do this because the boys are here year after year.

"We don't have to start again every season. We have the basis. Other full backs have defined the position before Trent and for sure he has as well.

"Where it can end and where it will go to, I do not know, but we have some ideas how we can evolve our game. It's tricky because of the lack of training time but maybe we will find some moments where we can work on this."