BERLIN (AFP) - Gerald Asamoah marked his full return from injury with a goal to help Schalke 04 tighten their grip on the Bundesliga with a 2-0 home win against tailenders Borussia Monchengladbach on Saturday.

After last week's 2-0 loss at Bayern, Schalke coach Mirko Slomka desperately needed a win to keep their advantage as the Ruhr side bid for their first Bundesliga title since 1958.

But with six games left this season - and their challengers VfB Stuttgart securing a 4-2 win over Hamburg, and champions Bayern a 2-1 victory at Hanover - the battle for the championship is far from over.

After a sluggish first half Schalke took control through a 57th-minute opener from Germany striker Asamoah, who was starting his first match since the horrific double leg fracture he suffered last September.

Striker Kevin Kuranyi then broke his goal drought when he added a second after 71 minutes.

"It was hard-fought, but we completely deserve this win," said Slomka.

The win lifts Schalke, who have won just one of their six away games in the Bundesliga, four points clear of VfB Stuttgart (52) who move into second spot ahead of Werder Bremen.

Werder Bremen, who have 51 points, can however reclaim second spot on Sunday when they host Nuremberg.

Fourth-placed Bayern, whose 2-2 draw at AC Milan on Tuesday has left them with one foot in the Champions League semi-finals, are six points behind the leaders.

The reigning champions proved they can never be ruled out as they bounced back after going a goal down a minute before the break through Hanover's Dutch midfielder Arnold Bruggink.

Martin Demichelis got the equaliser after 52 minutes and Bastian Schweinsteiger the winner after 70.

Bayern captain Oliver Kahn said: "The aim is to finish in a qualifying spot for the Champions League, but in football anything is possible, particularly when your rivals are having problems."

VfB Stuttgart proved their title credentials when they raced to a 3-0 lead after just 27 minutes at Hamburg thanks to goals from Brazilian striker Cacau (10), Sami Khedira (13) and Roberto Hilbert (27).

Fernando Meira scored the fourth six minutes after the break before Hamburg hit back with goals from Czech midfielder David Jarolim (67) and Croatia striker Ivica Olic (76).

At the other end of the table the frantic scramble to avoid the drop now includes 12 teams, with just five points separating seventh-placed VfL Wolfsburg and the team they beat 3-2 Saturday, Mainz 05, who are in 17th position.