Kicking off the 22nd round of Bundesliga fixtures with the chance of cutting Bayern Munich’s lead to just three points, Dortmund wasted little time in front of their thunderous home fans.
A pinpoint Ryerson free-kick delivery from the edge of the box unlocked the Mainz defence in the 10th minute, allowing Serhou Guirassy to power a header beyond Daniel Batz – a league-high 10th Bundesliga opener from a set piece for BVB.
Just five minutes later, Niko Kovač’s side doubled their advantage when Ryerson again lofted a ball in from a similar position, this time finding Maximilian Beier, who squeezed in a header from a tight angle at the back post.
Mainz had opportunities to halve the deficit, but Silas was unable to guide his side-footed effort on target, having possibly strayed offside, shortly before Silvan Widmer slotted through Gregor Kobel’s legs from a confirmed offside position.
Those missed chances proved costly ahead of the half time interval, as Guirassy netted his second of the game and 11th in the league, nodding in from a Ryerson corner inside the six-yard area.
Unwilling to sit back, Dortmund peppered the Mainz goal after the restart, forcing Batz into saves to deny Felix Nmecha’s side-foot attempt before also thwarting Beier’s whipped strike and a low drive from Brandt.
With an hour played, Guirassy came within inches of bagging a hat-trick, nodding wide from point-blank range after another dangerous corner kick.
The hosts were firmly on top heading into the final stages, and Ryerson could have added an incredible fourth assist had Batz not beaten substitute Fábio Silva to the ball.
Yet with six minutes to play, Dortmund deservedly got their fourth and final goal, benefitting from Dominik Kohr’s OG after yet another Ryerson delivery.
As a result, Dortmund remain the only Bundesliga side yet to suffer a home defeat (W9, D2), conceding just eight goals at the Westfalenstadion and keeping seven clean sheets – each league bests.
More importantly, another win keeps the pressure on Bayern, who sit three points ahead of Dortmund with a game in hand.
As for Mainz, just a second loss in six league games (W4) is far from a disaster, yet Die Nullfünfer could still be sucked back into danger, sitting only two points above the relegation play-off spot ahead of the rest of the weekend fixtures.
Flashscore Man of the Match: Julian Ryerson (Borussia Dortmund)