Nintendo Switch Online subscribers will be able to download and play Mario Tennis Aces for free from 7th to 13th August as part of a new "Game Trials" scheme.
Game Trials is looking to be Nintendo's new system for letting players have a go at a full game before committing to buying it. Alternatively, I suppose you could take it as a challenge to see how fast you can complete Mario Tennis before the free trial runs out.
This is the first game to be included as a Game Trial in the UK, whereas Japan recently saw Captain Toad: Treasure Tracker announced as free this month.
Between 7th and 20th August, Mario Tennis Aces will also be available to buy for 33 percent off, and you don't have to worry about losing any progress after the trial ends as it will all carry over if you decide to purchase it.