* Hoffenheim earn surprise draw 3-3 at Bayern
* Bayern's Spain midfielder Alcantara injured
* Reus scores hat-trick in Dortmund victory (Updates with Guardiola quotes, Freiburg win)
By Karolos Grohmann
March 29 (Reuters) - Hoffenheim surprisingly ended champions Bayern Munich's 19-game Bundesliga winning streak with a 3-3 draw after taking the lead and then fighting back from two goals down on Saturday.
Last season's treble winners Bayern, who are likely to be without their Spain midfielder Thiago Alcantara for both legs of the Champions League quarter-final with Manchester United after he limped off with a suspected ligament injury, did manage to stretch their unbeaten domestic league run to 53 games.
Hoffenheim's Anthony Modeste silenced the Munich crowd, whose side secured the 2013/14 title at Hertha Berlin on Tuesday, by slotting in a 23rd minute goal.
The hosts, with a largely second-string team ahead of their first leg at United on Tuesday, then responded with three goals in an explosive nine-minute spell before a Hoffenheim comeback.
"Hoffenheim deserve congratulations because they played a very good pressing game," Bayern coach Pep Guardiola told reporters.
"But in the first half we were able to solve that problem. In the second half we were not good. We need to control the ball and when that is not the case we have a problem. We certainly must improve," he said.
Peruvian Claudio Pizarro, making a rare start in coach Pep Guardiola's rotation, struck in the 31st and 40th minutes and Xherdan Shaqiri added another in the 34th as the Bavarians seemingly restored order.
With convicted former Bayern president Uli Hoeness back in the stands before he starts serving a 3-1/2 year jail sentence for tax evasion, Hoffenheim battled back.
Sejad Salihovic's fierce free kick again beat Bayern keeper Tom Starke, replacing the rested Manuel Neuer, to cut the deficit a minute before the break and Roberto Firmino completed what amounts to an upset result against Bayern in the 75th.
Germany international Reus was in scintillating form after Stuttgart shocked his visiting Dortmund side, who play at Real Madrid in the Champions League last eight on Wednesday, with two goals in the opening 19 minutes to take a firm grip on the game.
Christian Gentner put the home side ahead and Martin Harnik doubled their lead from point blank after a fine solo effort from Ibrahima Traore.
Reus' fine finish on the half hour put Dortmund back in the game and they turned up the heat in the second period with Robert Lewandowski hitting the woodwork and Reus firing narrowly wide.
He then converted a spot kick in the 68th and clinched the winner seven minutes from time to keep Dortmund a point ahead of Schalke 04 with six games left in the season.
Stuttgart, who were left with 10 men after a second booking for Georg Niedermeier, are in 17th place on 24 points.
There were more jeers than cheers in Leverkusen where fourth-placed Bayer had to settle for a 1-1 draw against bottom side Eintracht Braunschweig.
VfL Wolfsburg, in fifth, moved within a point of Leverkusen thanks to Brazilian Naldo's stunning 30-metre shot in the last minute to give them a 2-1 victory over Eintracht Frankfurt.
Freiburg snatched a 3-2 win over Nuremberg to move up to 13th, five points away from the relegation zone. Nuremberg, who had Emanuel Pogatetz sent off in stoppage time for a second booking, are 15th. (Reporting by Karolos Grohmann, editing by Alan Baldwin and Ken Ferris)