Guirassy has scored four goals in this season's Champions League
At a glance
Serhou Guirassy heads Dortmund ahead after delayed kick-off
Maximilian Beier doubles German club's lead before the break
Return leg takes place in Bergamo on Wednesday
Borussia Dortmund will take a two-goal lead into the second leg of their Champions League knockout phase play-off tie after a routine home win against Atalanta.
After the game was delayed by 15 minutes because of the Bundesliga club encountering traffic problems on the way to the stadium, the hosts took the lead inside three minutes through forward Serhou Guirassy.
The Guinea international rose highest to connect with Julian Ryerson's cross and head home his 16th goal of the season.
The 1997 winners continued to dominate and doubled their lead in the 42nd minute when Guirassy turned provider and crossed for Maximilian Beier to tap in at the back post.
Despite enjoying a greater share of the ball in the second half, Atalanta were unable to ever really test home keeper Gregor Kobel.
The return leg takes place in Bergamo on Wednesday, 25 February (17:30 GMT)
