Berlin (AFP) - Naby Keita and Timo Werner netted second-half goals to seal RB Leipzig's 2-0 win at Hamburg on Friday to give the Bundesliga club a confidence boost before their Champions League debut.

It was an important win for Leipzig who play in the Champions League for the first time at home to Monaco on Wednesday.

Liverpool-bound Keita, who will join the Merseyside club for the 2018-19 season, gave Leipzig the lead in Hamburg on 67 minutes when the Guinea midfielder fired home from 20 metres out.

Leipzig's goalkeeper Peter Gulacsi then stopped Hamburg from equalising with a superb save to deny Hamburg striker Sven Schipplock.

Germany striker Werner doubled Leipzig's lead with 15 minutes to go when RB's new signing Kevin Kampl threaded a pass to the 21-year-old who fired home.

Werner has now scored five goals in his last four games for club and country, including netting twice in Germany's 6-0 rout of Norway last Monday which left the world champions on the verge of qualifying for next year's World Cup Finals in Russia.

Werner was denied a penalty in Hamburg by the video assistant referee (VAR) on the stroke of half-time when he appeared to have been brought down in the box.

Referee Deniz Aytekin awarded a penalty, but the VAR reversed the decision when replays showed Hamburg midfielder Albin Ekdal made contact with the ball before bringing Werner down.

The VAR is being trialled in the German league for the first time this season.

"We deserved the win," said Leipzig coach Ralph Hasenhuettl. "We had a lot of chances in the first half, but a goal was missing and then there was the penalty situation.

"In the second half, we focused on our strengths and it paid off."

The result leaves Leipzig third in the table behind leaders Borussia Dortmund and defending champions Bayern Munich who play Freiburg and Hoffenheim respectively on Saturday.