Berlin, Feb 14 : Borussia Dortmund strengthened its pursuit of leader Bayern Munich with a comprehensive 4-0 home victory over Mainz, extending its unbeaten Bundesliga run and maintaining a three-point gap at the summit.

The result stretched Dortmund's sequence without defeat to 15 league matches and halted Mainz's recent surge, as the visitor's winning streak came to an end in the opening fixture of the 22nd matchday.

Niko Kovac's side asserted control early, dominating possession and forcing Mainz deep. Its first clear opportunity brought the breakthrough after 10 minutes. From the right edge of the area, Julian Ryerson delivered a precise cross and Serhou Guirassy rose above Dominik Kohr to head in from close range.

Five minutes later, the pattern repeated. Ryerson again found space to cross, this time picking out Maximilian Beier at the far post. His header from a tight angle struck Daniel Batz and crossed the line for 2-0.

Mainz briefly threatened a response when Silas ran clear following a defensive lapse, but he steered his effort wide. The miss proved costly. Shortly before the interval, Ryerson's corner caused further problems and Guirassy powered home another header to make it 3-0, effectively deciding the contest before the break.

After halftime, Dortmund remained the more dangerous side. Batz denied Julian Brandt and Guirassy in quick succession, yet Mainz struggled to generate sustained pressure despite occasional approaches.

The fourth goal arrived in the 84th minute. Another Ryerson corner deflected off Dominik Kohr and rolled into his own net, completing a night in which the Norwegian assisted all four goals. Gregor Kobel preserved the clean sheet with a late save, ensuring Mainz finished empty-handed.

Dortmund remain second and trim the gap to FC Bayern to three points, increasing the pressure on the leaders before their next fixture, while 14th-placed Mainz continue to hover above danger, sitting just two points clear of the relegation play-off position.

"We are happy and we are pleased with the win. In the first half we were very efficient and directed the game the way we wanted. After the break we controlled it. A 4-0 is very good, and above all keeping a clean sheet is important for us. We are not looking at Bayern now. We are looking behind us because our clear objective is to qualify for the Champions League," Dortmund coach Niko Kovac said.

/IANS