After edging a competitive first set 7-6, Tsonga needed just 24 minutes to win the second 6-0, with his opponent visibly struggling with a back injury.
Tsonga's serve was broken in game three as Nishikori established an early 3-1 lead on Grandstand Court.
However, the Frenchman levelled the opening set by breaking back in game eight, before forcing Nishikori to serve to stay in it at 5-6.
The Japanese number one saved a set point en route to forcing a tie-break, in which he led 3-0 and 4-3.
However, Tsonga soon found another gear, enabling him to prevail 7-5, sealing the opening set after 65 minutes.
The trainer was then called to do some work on Nishikori's lower back during the change of ends.
With Nishikori in clear discomfort, the second set was a non-event. Tsonga quickly won 24 of 30 points, sealing victory with his 13th ace of the match.