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Dortmund saw title rival Bayern Munich hammer Stuttgart 5-1 on Satrday (AEST), and Niko Kovac's team did make a flying start at Signal Iduna Park.

Guirassy needed just nine minutes to open his account for the season, tucking home after neat play from the impressive Konstantinos Karetsas.

Dortmund peppered Hamburg's goal from there, but Daniel Heuer Fernandes stood firm, making standout saves to deny Felix Nmecha and Karetas.

However, Hamburg's luck ran out when, on the cusp of half-time, Giannis Konstantelias's wayward effort diverted in off Sebastiaan Bornauw.

Patson Daka went close for Hamburg in the second half, hitting the post with a curling attempt, and the visitors were handed impetus in the 77th minute.

Just on as a substitute, Samuele Inacio slid in late on Albert Gronbaek and received his marching orders. Hamburg, though, could not make their numerical advantage count.