Borussia Dortmund blew the Bundesliga title race wide open with a 4-1 win over Hertha Berlin on Sunday, but in-form striker Karim Adeyemi limped off clutching his hamstring in the first half.
The win saw Dortmund pull level on points with league leader Bayern Munich and high-flying Union Berlin, which was held to a 0-0 draw at home to Schalke 04 earlier on Sunday.
Bayern Munich dropped a 3-2 decision at Borussia Moenchengladbach on Saturday. It was reduced to 10 men after eight minutes when France defender Dayot Upamecano was ruled to have brought down a charging Alassane Plea on the edge of the box.
Union missed the opportunity to leapfrog Bayern into first with a miserable draw at home to bottom club Schalke, which has now battled to a league record four goalless draws in a row.
Bundesliga's American connection ...
• Borussia Dortmund's Gio Reyna was an unused substitute for Borussia Dortmund for the second consecutive game. He scored in three straight appearances off the bench but has been limited to 66 minutes in four games since then ... U.S. international Jordan Pefok missed a chance to snatch a late winner for Union Berlin in its 0-0 tie with Schalke 04 when he skied a tough chance high over the bar from close range on 81 minutes ... Joe Scally, who has been battling a calf injury, was also an unused substitute for Gladbach in its win over Bayern ... John Brooks started for Hoffenheim in its 1-0 loss at Ausgburg, its four straight loss in Bundesliga play since he arrived from Benfica and immediately stepped into the starting lineup ... Kevin Paredes was ill and did not dress for Wolfsburg's 3-0 loss to RB Leipzig.
"We're on a great run of form and we want to keep riding this wave and see where it leads in the end," said Dortmund captain Marco Reus.
Adeyemi's injury made for a bittersweet evening, with the 21-year-old limping off almost in tears just minutes after putting his side on their way with a quickfire goal and assist.
Dortmund started a little sluggishly after their 1-0 Champions League win over Chelsea in midweek, and Hertha could have taken the lead when Jessic Ngankam skimmed the bar early on.
The Signal Iduna Park was soon bouncing, though, as Adeyemi gave Dortmund the lead with a brilliant backheel on 27 minutes.
Adeyemi set up Donyell Malen for his side's second with a brilliant cross four minutes later, but was already clutching his hamstring as he curled the ball into the box.
After the match, Dortmund coach Edin Terzic said Adeyemi "would probably miss a few games" but asked for "a little time" so the club could get an official diagnosis.
There was fresh hope for relegation-threatened Hertha when Lucas Tousart thundered the ball in off the bar just after the break to halve Dortmund's lead.
But Dortmund overcame their nerves once more and Reus smashed a direct free-kick into the top corner to restore the two-goal cushion.
Julian Brandt made it four late on, linking up with Jamie Bynoe-Gittens to score for a third league game in a row.
In one of the most intriguing Bundesliga title races for years, Dortmund, Union and Bayern are now all on 43 points after Bayern's surprise defeat to Borussia Moenchengladbach on Saturday.
"There's a long way to go yet, not just for us, but also for Union and Bayern," said Brandt.
© Agence France-Presse