Jurgen Klopp must be heading home from Hoffenheim satisfied after Liverpool sealed a 2-1 win in the first leg of their Champions League qualifier.Trent Alexander-Arnold won many of the plaudits after the 18-year-old opened the scoring with a beauty of a free-kick.Simon Mignolet was equally impressive, saving an albeit tame penalty, and Sadio Mane shone in attack - though that probably goes without saying.With the Bundesliga outfit noted for their set-pieces, this was a game that could have gone horribly wrong for the Reds, but they've managed to escape relatively unscathed and with two away goals in the bag.However, that's not to say there weren't some worrying moments.Alberto Moreno looked to be struggling with his positioning, particularly when Hoffenheim put balls in over the top.Klopp is doing his best to reintegrate the Spaniard after a decent pre-season and while he had a couple of OK contributions, his overall performance didn't really help his case for keeping James Milner out of the starting XI.The left-back wasn't the only one, though, as Dejan Lovren endured a night to forget. The centre-back wasn't at his best in the weekend's 3-3 draw with Watford and sadly, he wasn't able to rediscover his form in time for the trip to Germany.

Lovren struggled 

Lovren was at fault for conceding the penalty. Former Arsenal winger Serge Gnabry first nutmegged him in the box and then tricked him into tripping him up all in one movement.

Take a look:

Fortunately for the Croatian international, it didn't make too much difference as his compatriot Andrej Kramaric missed from 12 yards.

Had the hosts had their way, they might have had another spot-kick from a Lovren hand-ball, although that would have been a little harsh. 

Liverpool fans react 

This wasn't the 28-year-old's finest hour and plenty of Liverpool fans were dismayed:

What does Klopp need to do about the defence? Have your say in the comments.