BERLIN (AP) -- With Bayern Munich comfortably clear in the Bundesliga, defending champion Borussia Dortmund visits Bayer Leverkusen on Sunday for a clash likely to decide second place -- and possibly even more.
Dortmund is 12 points behind Bayern and one behind Leverkusen, but Juergen Klopp's side appears revitalized after the winter break, having scored eight goals without reply in two games.
Last season, Dortmund stayed unbeaten after the winter break to overtake Bayern with 15 wins and two draws before finishing the Bundesliga with a record 81-point haul.
The gap at the time was three points, however, and Klopp has acknowledged that the best Dortmund can realistically hope for this season is second place due to Bayern's outstanding form in the first half of the season.
"I worked it out: We need 51 points from the second half, the maximum from 17 games. Then take away 12 points for the gap on Bayern. Makes 39 the most Bayern can get. Is that realistic? No," Klopp told Sport-Bild magazine. "Borussia as champions this season -- that's ridiculous. But our aim is to overtake Leverkusen."
However, even that comment doesn't mean Klopp has completely given up on the title.
"If a cog doesn't quite catch for Bayern sometime, then we'll go on the attack again," he said.
Bayern faces a tricky tie at Mainz on Saturday, amid reports of dressing room discontent as Jupp Heynckes struggles to give all of his stars match time.
Dutch winger Arjen Robben and Germany striker Mario Gomez were reportedly unhappy not to get more playing time in last weekend's somewhat flattering 2-0 win at Stuttgart, with their replacements Thomas Mueller and Croatian striker Mario Mandzukic both scoring.
Gomez, who made his injury comeback in November, went on as an 89th-minute substitute while Robben didn't play at all.
"I understand that the players aren't happy with their situation but that doesn't play a role for me," Heynckes said. "Everyone here has to accept it."
Mandzukic is one of three players with 12 goals, one less that Leverkusen's top-scorer Stefan Kiessling, while Kicker magazine reported that Mueller produced more crosses than Robben.
Mainz is fifth, with five wins from its last seven games across all competitions, but coach Thomas Tuchel knows Saturday's will be the toughest test yet.
"To my mind they are the most talented team in Europe, along with Barcelona. It's certainly the most difficult task to beat them," Tuchel said Thursday. "We need to hit our absolute top level, both mentally and physically. But if Bayern hit their top level, ours won't be enough."
Schalke, which Mainz knocked out of the German Cup, hosts bottom side Greuther Fuerth on Saturday, with coach Jens Keller under pressure to stop the alarming mid-season slump that led to the departure of his predecessor, Huub Stevens.
Schalke will be able to call on new signing Michel Bastos, who arrived on loan from Lyon to replace the Tottenham-bound Lewis Holtby.
Also on Saturday, fourth place Eintracht Frankfurt visits Hamburger SV, Wolfsburg hosts Augsburg, Fortuna Duesseldorf plays Stuttgart and relegation-threatened Hoffenheim hosts in-form Freiburg.
Hoffenheim dropped former Germany goalkeeper Tim Wiese from its squad Thursday, replacing the 31-year-old with Tottenham reserve goalkeeper Heurelho Gomes on loan until the end of the season.
"He will play his part in ensuring Hoffenheim stays in the Bundesliga. I am certain of that," said Hoffenheim manager Andreas Mueller, whose side is second from bottom with the worst defense in the league.
Nuremberg hosts improving Borussia Moenchengladbach on Sunday, when it hopes to bounce back from last weekend's 3-0 loss to Dortmund.
Werder Bremen, which lost 5-0 to Dortmund the week before, opens the 20th round of games at home to Hannover on Friday.