Berlin, Aug 28 (IANS): Champions Bayern Munich salvaged a late 1-1 draw against Borussia Monchengladbach on Saturday to remain top of the Bundesliga after matchday four -- on goal difference over their next opponents Union Berlin.

Germany winger Leroy Sane fired an 83rd-minute equaliser into the bottom left corner after Sadio Mane had two first-half goals disallowed for offside and Gladbach goalkeeper Yann Sommer had frustrated Bayern with 19 saves, the biggest number since data collecting started, according to statisticians Opta, reports DPA.

Gladbach had taken the lead in the 43rd against the flow of play from Marcus Thuram after a terrible blunder from Bayern defender Dayot Upamecano, who had also looked bad in Bayern's 5-0 German Cup meltdown 10 months ago against Gladbach.

Bayern dropped their first points of the season ahead of their trip next Saturday to Union who celebrated their biggest Bundesliga victory 6-1 at Schalke earlier Saturday and are level on 10 points with them.

One point back are Hoffenheim, Freiburg and Borussia Dortmund, who returned to winning ways after their shocking meltdown from 2-0 up in the 89th to a 3-2 defeat against Werder Bremen last week with a 1-0 at lowly Hertha Berlin from the first goal by new signing Anthony Modeste.

Bayern dominated from the outset with Leroy Sane forcing Yann Sommer to an early big save before Sadio Mane thought he had scored in the 34th and 39th only for Sane to be offside on the first occasion and Mane himself offside on the second occasion.

Gladbach had not threatened at all but took the lead when Christoph Kramer hit a speculative long ball into Bayern's half, Upamecano made a mess out of a clearance which allowed Thuram to run at Manuel Neuer and beat the Bayern and Germany captain with a low shot.

Bayern pressed for the equaliser after the break but Sommer made sensational saves before finally being beaten by Sane's effort off substitute Jamal Musiala. Sane's replacement Matthijs de Ligt was then also denied by Sommer in stoppage time as Bayern finished with 32 shots to Gladbach's five.

"Yann Sommer always plays well against us. He was the best man on the pitch," Bayern midfielder Joshua Kimmich told Sky. "We had absolute control but then had an unfortunate mistake."

Sommer said: "It was really tough. We knew what to expect. I am happy I had a good performance."

Union continued their strong start into the season with the big win at Schalke with the help of braces from Sheraldo Becker and Sven Michel.

Schalke defender Maya Yoshida said Union were playing "like Leicester City a few years ago" en route to the 2016 Premier League title but Union coach Urs Fischer firmly kept his feet on the ground, saying "the result was too high in the end."

Modeste, signed after Sebastien Haller became sidelined indefinitely with testicular cancer, headed Dortmund's winner in the 32nd minute and then celebrated with coach Edin Terzic "because he has always backed me."

"We had so many chances and in the end are happy to have won after what happened last week," he added.

Elsewhere, nine-man Bayer Leverkusen got their first points of the season 3-0 in Mainz; RB Leipzig got a maiden victory 2-0 against Wolfsburg; Hoffenheim beat Augsburg 1-0; and Freiburg also won 1-0, against bottom side Bochum, on Friday.