The American got by his Serbian opponent in straight sets to reach the second round in Madrid.
Like a steadily rising tide, fresh generations are taking the reins of US tennis
Madison Keys and John Isner were left frustrated after exiting Miami Open.
The American was pushed to his limits in a three-set win over the Spaniard to reach the second round.
Isner already holds the record for longest match ever played. Now he holds the record with Opelka for the longest tiebreak.
The 6ft 10 American is through to the next round after a tough three-set win that included a long rain delay.
The 6ft 10 American got revenge on his American opponent for the loss he suffered last week in Los Cabos.
Brandon Nakashima stunned John Isner to reach the final in Los Cabos.
John Isner will face Brandon Nakashima in the Los Cabos semi-finals.
The American was pushed to the limits by his Russian opponent beating him in three tight sets.
The American is in Los Cabos, Mexico looking to start the hardcourt season on the right foot.
The American was dominant behind his first serve where he won 53 out of 58 points played.
The American has got off to a winning start at Roland Garros.
John Isner is into the Madrid quarter-finals after a last set tiebreak win over Andrey Rublev.
John Isner is into the second round in Madrid after beating Miomir Kecmanovic in straight sets.
John Isner took to Twitter to raise some issues about the ATP and latest state of affairs in Tennis.
The young American is through to the semifinals after beating the number two seed.
The world No.21 believes players have to 'learn and adapt' to the virus.
There has been a big upset at the American hard court tournament.
Ubitennis looks at the biggest movers in this week's ATP rankings.