John Isner suffers surprise defeat in Cincinnati

Sam Querrey has booked his place in round two of the Cincinnati Open with an impressive triumph over 11th seed John Isner.

The pair possess two of the biggest serves on the ATP Tour but Querrey broke Isner's serve on two occasions on the way to a straight-sets win.

Both breaks of serves came in the opening set as Isner only won 51% of points behind his own delivery, while Querrey dominated at the other end by winning all but one point on his first serve.

Isner improved during the second but Querrey shut him out at the other end, eventually winning a tie-break to wrap up a 6-3 7-6 victory.