Bayer Leverkusen manager Xabi Alonso was critical of his team's poor start in their 5-2 comeback victory over Heidenheim on Saturday.

The current Bundesliga champions went two goals down inside the opening 21 minutes at the BayArena, before battling back to hammer their visitors.

The teams went in level at half-time, while Patrik Schick completed a hat-trick in the second half to secure their second victory in seven league games.

"The first 20 minutes were hard, hard on the pitch and hard mentally," Alonso told a press conference.

"They bullied us in midfield. We could not find any good situations.

"We then managed to find better solutions after the break, and we were more stable. That was the key to the better second half."

Leverkusen are fourth in the Bundesliga, nine points behind league leaders Bayern Munich. They improved significantly after Heidenheim forward Marvin Pieringer was taken off injured in the 28th minute, having suffered due to his pace prior to that.

"We had a bit of a doubt at the start, it was too hectic, we were too nervous," he added.

"We could relax a bit during the break, and then we saw a much better second half, with more control and more stability. Mentally, we were much better."

Aside from their poor start, Alonso singled out Schick in particular for praise after the game, with his perfect hat-trick having helped win the match for the hosts.

Schick has now scored 3+ goals in a Bundesliga game on three occasions for Leverkusen - only Ulf Kirsten (seven) has done so more times for the club.

"It was a perfect hat-trick. It is so important for a striker to get into this rhythm, to have that feeling and with us having a lot of matches during this time," said Alonso.