The Latvian forward netted five minutes into the second half to settle a close contest and lift his side a point above Mainz in the final Europa League berth.
In the day's other fixture, Eintracht Frankfurt continued their scoring struggles with a goalless draw at Hannover.
Success for the visitors would have restored them to fourth spot but instead they stretched their goal drought to five consecutive league matches in a stalemate.
Bayern Munich were made to fight before finally seeing off Fortuna Dusseldorf 3-2 in their Bundesliga clash at the Allianz Arena.
The win extended Bayern's lead at the top to 20 points as Borussia Dortmund lost 2-1 at derby rivals Schalke.
The win sent Schalke up to fourth, seven points behind their opponents and six below Bayer Leverkusen, who missed the chance to go second by losing 1-0 at Mainz.
Wolfsburg eased their relegation worries with a thumping 5-2 win at Freiburg.
Hoffenheim picked up a crucial victory in the fight against the drop with a 3-0 success at bottom club Greuther Furth.
In the late kick-off Borussia Monchengladbach and Werder Bremen drew 1-1.
In Friday's game, Augsburg's bid to survive to drop was dealt a blow as they fell to a 2-1 home defeat to Nuremberg
Sunday's Bundesliga Results
Saturday's Bundesliga Results
Friday's Bundesliga Results