Third-seeded John Isner became the first upset of the Mexican Open, losing 7-6 (4) 7-6 (5) to Croatia's Ivo Karlovic in the first round Tuesday.
Karlovic served 15 aces and Isner fired eight in a matchup between two of the game's biggest servers that was decided by a record-equaling eight consecutive tie-breaks..
A visibly upset Isner said after the match "I*m very disappointed, obviously."
Joao Sousa of Portugal came back to defeat Frenchman Adrian Mannarino 1-6, 6-2, 6-2 to advance to a second-round encounter against the winner of the later match between Andy Murray and Pablo Andujar.
South Africa's Kevin Anderson downed Stephane Robert of France 6-2 , 7-6 (7) and will next play America's Sam Querrey, while Spaniard Feliciano Lopez had a 6-4, 6-2 victory over France's Edouard Roger-Vasselin.