Grosskreutz does the trick for Dortmund

(CNN) -- A second-half strike by Kevin Grosskreutz earned Borussia Dortmund a 1-0 win at relegation-threatened Hertha Berlin on Saturday to extend their lead at the top of the Bundesliga.

The German midfielder's acrobatic overhead kick in the 66th minute proved enough to extend the reigning champions' lead to three points after Bayern Munich could only draw 0-0 away to bottom-of-the-table Freiburg.

Hertha remain in 15th place with 20 points but will hope new coach Otto Rehhagel, who led Greece to victory in the European Championships back in 2004, can turn their season around when he takes over on Sunday succeeding Michael Skibbe who was sacked last weekend.

With Bayern dropping points, Borussia Moenchengladbach move up to second place in the table with a 2-1 win at Kaiserslautern.

Midfielder Patrick Herrmann opened the scoring in the ninth minute before a shoulder injury forced him off later in the game.

Venezuelan Juan Arango doubled the lead five minutes later.

Danish defender Leon Jessen pulled one back for the home side in the 63rd minute but a much needed equalizer never materialized leaving Kaiserslautern languishing in 16th place with 20 points.

Werder Bremen triumphed in the north German derby beating Hamburg 3-1 at the Imtech Arena.

The visitors went ahead in the ninth minute thanks to a goal from Marko Marin with 18-year-old midfielder Tom Trybull scoring his first league goal on the stroke of halftime to make it 2-0.

With 14 minutes remaining Hamburg pulled one back when Mladen Petric scored from a free-kick but Austrian striker Marko Arnautovic made sure of three points for Bremen four minutes from the end.

Bayer Leverkusen stay in sixth place after a 4-1 win over second-from-bottom Augsburg, while Nuremberg are up to 12th thanks to a 2-1 win over Cologne.

Schalke take on Wolfsburg on Sunday while Hanover host Stuttgart.

Meanwhile in England, Arsenal suffered a miserable end to a desperate week as Sunderland beat them 2-0 at the Stadium of Light in the fifth round of the FA Cup.

A 40th minute strike by Kieran Richardson and an own-goal from Alex Oxlade-Chamberlain 12 minutes from the end rubbed salt in the wounds of a 4-0 defeat to AC Milan in the Champions League on Wednesday.

Robinho brace helps Milan thrash Arsenal

Over in West London things show no sign of improving for Chelsea as they were held to a 1-1 draw by Championship-side Birmingham City at Stamford Bridge.

Under-pressure manager Andre Villas-Boas saw his side concede a goal and miss a penalty (Juan Mata's shot being pushed onto the post by keeper Colin Doyle) in the first half.

Daniel Sturridge's 62nd minute strike spared the Blues' blushes but it wasn't enough to placate the home fans who booed their players off the pitch at the end of the match.

Chelsea travel to Napoli on Tuesday to play the first leg of the last-16 Champions League tie.

Fellow Premiership team Everton fared better though, beating Blackpool 2-0 at Goodison Park and Bolton Wanderers enjoyed the same margin of victory away to Millwall.

But Norwich City went down 2-1 to Leicester City at Carrow Road.