BERLIN - Hamburg SV scored twice in the first half to beat visitors Energie Cottbus 2-0 on Sunday and stay within four points of Bundesliga leaders Hertha Berlin. Fourth-placed Hamburg are level on 45 points with VfL Wolfsburg, who beat Schalke 04 4-3 on Friday and second-placed Bayern Munich, 3-0 winners at VfL Bochum on Saturday. Hertha, who beat Bayer Leverkusen 1-0 on Saturday, have 49 points. In a lacklustre match Hamburg needed only a brief good spell to sink Cottbus closer towards relegation. The goals came in a seven-minute period with striker Ivica Olic heading in a Mikael Tavares cross before Piotr Trochowski, who came on for injured Mladen Petric, doubled the lead with a long-range free kick in the 39th minute. Cottbus, one spot off the bottom of the table on 20 points, threatened only rarely and seemed resigned to their fate. "You could call this a workmanlike win. It may sound terrible but it is important for us," Hamburg coach Martin Jol told reporters. Jol will have to do without Petric for about two weeks after the Croatian striker tore a thigh muscle. DIEGO MAGIC Tenth-placed Werder Bremen crushed VfB Stuttgart 4-0 with Markus Rosenberg scoring a brace after Diego and Claudio Pizarro had put them in the lead, ending Stuttgart's nine-match unbeaten league run since coach Markus Babbel took over in November. Werder grabbed the lead through a stunning Diego free kick, the Brazilian masterfully curling the ball over the Stuttgart wall and into keeper Jens Lehmann's top corner. Eight minutes after the restart Pizarro, on loan from Chelsea, unleashed a thundering drive from 22 metres for his 12th league goal of the season. Diego then picked out Rosenberg with a pin-point pass down the middle for the striker to slot home before the Swede also scored a second in the 74th minute in similar fashion with Alexandros Tziolis providing the pass. "Finally the team gets a great result," Werder coach Thomas Schaaf said. "What was also pleasing was the higher degree of efficiency in our game."