Kinect Sports Rivals

An Ace is when you score immediately when serving, or to put it another way, serve the ball and the other player misses the very first return. I found it very difficult to ever get a single Ace against the computer, even in my first easier games. So i imagine getting 4 in a row would take a combination of skill and luck. Maybe I wasn't doing it right, but the following method was much simpler.

I did this with two players on one console. You must have already created a character for two separate profiles. Start up the game and choose your character, then once you get to the Island / Main Menu, press to change characters. Choose one of the three empty squares and then choose the other profile. You will now have two characters shown on the island and you can swirl over to Tennis and choose the Event option at the top with the 2-player icon. Once you each raise your hands to start the match, simply serve the ball four times and have the other player just stand still.

Note: The achievement did not pop up for me when i did this, so i thought you couldn't do it in two-player mode. However, i noticed it said i unlocked it on this site, so it must have just glitched.

I assume you can also unlock this with a second player over Xbox Live. See my achievement for Tennis Champ for more details: