Costa dazzles as Bayern rout Hamburg in season opener

Bayern's established campaigners Robert Lewandowski, Medhi Benatia and Thomas Mueller, who netted twice, grabbed Bayern's first four goals with Brazil winger Costa adding the fifth to seal a show-stopping performance.

Costa, who Bayern coach Pep Guardiola has said can be the best winger in the world, showed why the champions paid Shakhtar Donetsk 30 million euros ($33.3m) for him in July.

The 24-year-old chested down a long pass before firing in a cross which led to Bayern's third goal, then hit the back of the next with a crisp left-footed shot on 87 minutes.

"He's a superb player, I understand him very well already and he's just going to get better with each game," was Lewandowski's verdict on Costa.

Bayern, who won last season's title by 10 points, are bidding to become the first team to win four Bundesliga crowns in succession in the third and final year of Guardiola's contract.

"It was tough in the first half, because Hamburg defended with six players, but we did better in the second half," said Guardiola.

"I am happy with the debuts of Douglas Costa and Arturo Vidal, they have a lot of quality and experience. They will help Bayern Munich a lot."

Hamburg, who only avoided relegation last season by winning a play-off for the second year running, had their share of early chances as ex-Tottenham Hotspur midfielder Lewis Holtby fired a fourth minute shot straight at Bayern goalkeeper Manuel Neuer.

But after Lewandowski headed over a Philipp Lahm cross on 22 minutes, Bayern got the breakthrough five minutes later.

Spain veteran Xabi Alonso curled in a free-kick and with five Bayern players free, Benatia headed home the first goal of the new season on 27 minutes.

Bayern doubled the lead after the break when Lewandowski fired home from close range.

Alonso delivered a long ball, which took a deflection and hung in the air and was cleared by Hamburg defender Matthias Ostrzolek into Lewandowski's path for the Poland striker to slot home on 53 minutes.

Brazil defender Rafinha nearly claimed their third moments later when he fired at Hamburg goalkeeper Rene Adler and the former Germany shot-stopper saved from point-blank range.

The floodgates opened when Costa chested down Mario Goetze's pass and the Brazilian did well to keep the ball in play before his pin-point header was headed home by Mueller on 69 minutes.

Mueller added Bayern's fourth on 73 minutes as Hamburg's defence left plenty of space to exploit.

Costa then capped an outstanding display when Ostrzolek lost the ball and Rafinha fed the Brazilian who hit the back off the net off his deadly left boot.