The result continued Del Potro's hot streak, after he won in California 10 days ago, beating Roger Federer in a compelling three-set final to claim a maiden Masters 1000 title. The 2009 U.S. Open champion is back to playing some of his best tennis in years after battling serious left wrist injuries that required three surgeries and threatened to curtail his career. He advances to face another big server, American John Isner, who overwhelmed South Korean Chung Hyeon 6-1 6-4 in an afternoon match. A fired up Isner yelled "Come on" and pumped his fist when he broke Chung's serve in the first set to race to a 3-1 lead, ending the Korean's streak of 27 consecutive holds of serve. The 14th-seeded Isner cruised through the remainder of the 25 minute opener, in which he fired seven of his 13 aces.
Juan Martin del Potro rolls on, beating Milos Raonic in a third set tiebreak to reach the Miami semifinals (vs Isner).Delpo has now won FIFTEEN straight matches. — Ben Rothenberg (@BenRothenberg) March 29, 2018
The hour-long contest was all but over once Chung sent a forehand long in the fifth game of the second set to hand Isner another break and a 3-2 lead. The 21-year-old was unable to find an answer to Isner's booming serve in a match where he failed to convert his only break point opportunity and was himself broken four times. Isner said the hot and windy condition in Miami, where the courts are not particularly fast but cause the ball to bounce high, suit his first-strike approach to the game perfectly. The other quarter-finals will be played Thursday. South African sixth seed Kevin Anderson faces Spanish 16th seed Pablo Carreno Busta in the afternoon, before an evening match between German fourth seed Alexander Zverev and Croatian 29th seed Borna Coric.
John Isner reaches the semifinals in Miami with a 6-1, 6-4 win over Chung. His *ELEVENTH* Masters semifinal. He could rejoin the top 10 on Monday, pending other results.— Ben Rothenberg (@BenRothenberg) March 28, 2018