MAINZ, GERMANY: Bayern Munich took back the top spot in the Bundesliga with a 3-1 win over Mainz on Saturday, while Borussia Dortmund's Erling Haaland made it seven goals from three games.

The league's top scorer, Robert Lewandowski, reached 22 with Bayern's opening goal against Mainz. Bayern will finish the week top of the league for the first time since September after Leipzig barely salvaged a 2-2 draw against 10-man Borussia Mönchengladbach.

Haaland's explosive start to life in Germany continued with two goals for Dortmund in a 5-0 hammering of Union Berlin. It was his first start in the Bundesliga after scoring five goals in two substitute appearances.

Bayern leads by a single point from Leipzig, with Dortmund and Gladbach two points further back.

BAYERN'S BACK

Bayern is back to its old self. Since the winter break, it's scored 12 goals in three Bundesliga games while chasing an eighth successive title.

Lewandowski got it started on Saturday with a simple headed goal off Benjamin Pavard's cross, and Thomas Müller and Thiago extended the lead.

The one setback for Bayern was Jeremiah St. Juste's goal for Mainz from a corner just before halftime. It was the first time Bayern conceded in a competitive match since December 18.

Mainz is 15th, one point above the relegation playoff spot, and has lost four straight Bundesliga games.

NKUNKU SAVES LEIPZIG

Leipzig started 2020 as the team with the best shot of breaking Bayern's hold on the title, but came close to back-to-back defeats before Christopher Nkunku's spectacular 89th-minute leveler.

Leipzig's defending verged on shambolic in the first half. First, Gladbach played the ball all around the box before Alassane Plea scored the opener. Then a wayward clearance conceded the ball for Jonas Hofmann to score the second.

However, unforced errors from Gladbach allowed Leipzig back into the game. Goalkeeper Yann Sommer dropped the ball in a collision with teammates, allowing Patrik Schick an easy finish. Then Plea was sent off, earning two bookings within a minute after a heated argument with the referee.

Leipzig's second goal was anything but a gift. Nkunku picked up the ball on the edge of the penalty area, shimmied past a defender, and slammed in a powerful shot.

Gladbach's fans protested against Leipzig. Many see the young club's rapid rise as energy drink company Red Bull buying success. Gladbach's supporters whistled for the first 19 minutes of the game. That was a nod to their club's founding date of 1900. It's 109 years older than Leipzig.

STORMING SANCHO

With all eyes on new signing Haaland, another 19-year-old Dortmund player has been racking up the goals.

Jadon Sancho scored Dortmund's opening goal in the win over Union Berlin, his 12th in 18 Bundesliga games this season, making him the youngest ever player with 25 Bundesliga goals. The England winger has failed to score only once in Dortmund's last nine league fixtures.

Haaland made it 2-0 in the 18th from a corner.

Dortmund scored five goals for the third game in a row and, encouragingly for a team with a sometimes fragile defense, kept a clean sheet for the first time since December 14.

LEVERKUSEN LACKING

Bayer Leverkusen's bid for Champions League football will depend on beating teams like midtable Hoffenheim, but on Saturday Leverkusen lost 2-1 after surrendering the lead.

That result makes the positions of the top four -- Bayern, Leipzig, Dortmund and Gladbach -- more secure in the Champions League spots, especially after sixth-placed Schalke drew at Hertha Berlin 0-0 on Friday.

Elsewhere, Werder Bremen lost to Augsburg 2-1. Fresh off beating Leipzig last week, Eintracht Frankfurt drew with relegation-threatened Fortuna Düsseldorf 1-1.