Solve Tennis Score Puzzle: Use Modular Arithmetic

[phyguy321]

In tennis, the players switch sides after the odd games. one hot sunday the auther found himself on the side where he had begun the match a while earlier. He knew the game score was either 6-2, 4-3 or 6-2, 5-4. which was it? you must use modular arithmetic to solve this

 

[Defennder]

Hmm, what does "odd games" refer to?