The dynamic midfielder netted Hamburg’s second in a 3-1 win last night.
The hosts found themselves 3-0 up against the title-chasing side after 55 minutes, with the 25-year-old doubling his team’s advantage just before half-time.
The result lifts Hamburg up to eighth in the Bundesliga table while simultaneously damaging Dortmund’s hopes of reeling in runaway leaders Bayern Munich.
Arguably his best moment in a Spurs jersey came when he scored a late, long-range winner for the North London outfit against Fulham at Craven Cottage.
Holtby went on to play for Fulham on loan before initially starting out at Hamburg on a temporary deal, which has since been made permanent.
The 25-year-old was a hard-working member of the Spurs squad but was not given a lot of time on the pitch due to the presence of Christian Eriksen.
Photos of Holtby celebrating can be seen below.