World number nine Venus Williams continued her dominance on home soil as she beat Greece star Maria Sakkari in the third round of the US Open.Williams won the contest in straight sets 6-3, 6-4 and entered the round of 16 to face Carlo Suarez Navarro next up.But one incident during the match has got more than a few people smiling this weekend.Known for her blistering serves, Williams has managed to maintain her power and speed throughout her pro career.However, it was that menacing serve that proved costly for one ball boy as the American fired over a slightly wayward one straight into him.The ball came hurling towards the young lad and hit him in the groin area, and although he tried to remain composed, the grimace on his face told the story - see the video below.Some might claim that the boy should have caught the ball to prevent it from hitting his private parts, but, needless to say, catching a Venus Williams serve is definitely not as easy as it looks in slow motion.Moreover, the entire affair was caught on video and has gone viral after it was posted on Twitter, which produced hilarious responses.Roger Federer's reaction was the best, though, as he perfectly expressed what everyone was thinking in a series of emojis on Twitter.

Federer's tweet has rightly gone viral, with over 60,000 likes and 31,000 retweets at the time of writing

Laughter for some while agony for the boy in question!