Twenty-two tennis players were individually studied on 2 occasions. They performed a prematch skill test, a 2-hr tennis match against an equally ranked opponent, and a postmatch skill test. A carbohydrate-electrolyte (CHO-E; Lucozade Sport) or flavor-matched placebo-electrolyte (PL) beverage was administered in a double-blind fashion. During the trials, heart-rate and movement intensity were monitored, and the match was recorded for performance analysis. There were no differences in skill-test scores pre- to postmatch or between trials (154±38 pre- and 160±35 postmatch on PL, 155±36 pre- and 165±33 postmatch on CHO-E). CHO-E ingestion elevated blood glucose concentration throughout the match, and participants reported feeling more energetic (general activation) and more tense (high activation) 1 hr into the match than at baseline (p<.05). Participants in the CHO-E trial spent more time in moderate-intensity activity and less time in low-intensity activity than on PL. Performance analysis revealed that CHO-E ingestion increased overall serve success (M±SD, 68%±7% for CHO-E vs. 66%±7% for PL; p<.05) and success of first serves (65%±9% for CHO-E, 61%±7% for PL; p<.01) and serves to the advantage side (70%±9% for CHO-E, 66%±7% for PL; p<.05). Return success was greater during the second set of the match (p<.05) in the CHO-E trial. Differences in serve and return success were not associated with blood glucose response to CHO or player ability.