The aim of this study was to compare heart rate (HR) and blood lactate to tennis-specific interval tests with 10-, 20- and 30 seconds and a work to rest ratio about 1:1. Six well-trained tennis players participated in this study. Each player completed an incremental test to volitional exhaustion in a tennis-specific shuttle run, where peak running speed (Vmax), first and second lactate turn points (LTP1, LTP2), maximum lactate (LAmax) and maximum HR (HRmax) were determined. The interval tests intensity was determined with 80% of Vmax. During the 20- and 30-seconds method a lactate steady state was build up. The 10-seconds method shows a higher lactate concentration at the end of the test. Results of mean heart rate (HRmean) showed no significant difference between the 10-, 20- and 30 seconds method. To analyse stroke quality under higher physiological responses, subjects were required to perform fore- and backhand strokes. For absolving the strokes, balls were thrown out by a ball machine. The comparison between higher physiological responses and stroke quality has shown no correlation.