John Isner has booked his spot in the quarter-finals of the Miami Open after beating fifth seed Milos Raonic 6-7 7-6 7-6 in a battle of two of the biggest servers on tour.

The crowd in Florida were treated to a stunning display of serving from both players as the first two sets of tennis passed by without a break point being offered by either man.

Both Isner and Raonic were keen to be aggressive on return, but openings were few and far between before a predictable tie-break was needed to decide the opener.

Two errors on serve in the tie-break handed the advantage to Raonic, and the Canadian capitalised to claim a 7-3 success.

The second set followed a similar pattern, and a straight-sets triumph looked to be on the cards when Raonic claimed two early mini-breaks in the next tie-break.

However, Isner responded impressively to keep the match alive before clinching the set to force the match into a decider.

The American would then be forced to save the only two break points of the match at the start of the third as Raonic missed the chance to claim an advantage.

It seemed inevitable that the fourth-round clash would be decided on a tie-break, and it was Isner who completed the comeback by earning a 7-5 triumph with the second match point to secure his progress.