Dortmund, Germany – Borussia Dortmund returned to the summit in the Bundesliga last weekend, but the defending champions will face a stern test Saturday against Bayer Leverkusen.
Dortmund is unbeaten in 14 straight, and with three successive wins since the league returned from its winter break, coach Jurgen Klopp's side has regained its favorite status to repeat as champions.
Although Dortmund struggled in European play once again this season, Klopp has put together the best side in Germany again. His side secured a semifinal spot in the Pokal Cup earlier this week.
Dortmund has not missed young star Mario Gotze, but any dip in form will prove fatal with Bayern Munich still on its heels in league play. The clubs are also on a collision course in the Pokal Cup, either in the semis or the final.
Klopp will not overlook Leverkusen this week as his opponents did advance into the last 16 of the Champions League, even though Bayer has struggled in league play recently with just one win in its last five.
"We know some things, but we don't know everything," Klopp said about Bayer.
Bayer has been a work in progress under first-year coach Robin Dutt, and could line up in a number of formations this week on the road.
With Barcelona awaiting in the Champions League on Tuesday, Leverkusen needs a boost and a win over Dortmund would provide the perfect medicine. But Dortmund has lost just once at home and dropped points twice in league play.
Leverkusen has been decent away from home with just two losses in 10 matches.
He suffered ankle ligament damage against Stuttgart in the Pokal Cup, but with Bayern through after a 2-0 road win, the team enters the league game with some confidence.
Coach Jupp Heynckes will have to shuffle his lineup, and decide whether Thomas Muller - who started against Stuttgart - or Arjen Robben gets the start on the right wing.
Bayern has played better this season without Robben, who has struggled to find top form after missing the early part of the season. Bayern played its best at that time, leaving Heynckes in a tough spot as to what to do with Robben.
Schalke travels to Monchengladbach in Saturday's other match involving top-six clubs, with third place on the line. Schalke currently sits third on 41 points - level with Bayern - while Gladbach is just one point back.
With the top four separated from the pack, the winner should emerge with one foot in the Champions League next season. Schalke, led by Klaas-Jan Huntelaar and his 16 goals, has the second-most goals scored this season (46). Gladbach has allowed the fewest (12).
"Gladbach are a well organized side. They defend well, switch the play quickly and like to have the ball in their attacking half," said Schalke manager Huub Stevens.
"Our opponents set out to keep the ball a long way from their own goal. That's clever. We have to be patient against such a team and when we create chances we have to make sure we take them."
Markus Babbel will debut as Hoffenheim's coach at Werder Bremen on Saturday, and Mainz hosts Hannover and Stuttgart hosts Hertha Berlin in the day's other matches.
Augsburg hosts Nurnberg and Cologne hosts Hamburg on Sunday to end the week's action. Wolfsburg hosts Freiburg on Friday to open the week's action.