Kei Nishikori, Jo-Wilfried Tsonga and John Isner all secured straight-set victories as they played their opening matches at Indian Wells on Sunday, but world number one Novak Djokovic had a tougher time of it, as did Rafael Nadal.
Djokovic, the first seed, was 4-0 down and went on to lose the first set against American Bjorn Fratangelo but rallied in the second to make short work of his unseeded opponent thereafter.
Nadal won his first set against Gilles Muller well but had to tie up the match in three sets, while Nishikori enjoyed much plainer sailing, as did Tsonga despite a tough opening set against Vincent Millot.
Just three of the 16 seeds in action were eliminated, among them 19th seed Benoit Paire.
SEEDS SNEAK THROUGH
Djokovic made a sluggish start to his Indian Wells defence as he found himself 4-0 down against Fratangelo, before losing the first set 6-2.
The Serbian, usually so calm and collected, showed signs of frustration throughout but found top gear in the second and third set to win the match 2-6 6-1 6-2.
Fifth seed Nishikori made light work of his opponent, beating Mikhail Kukushkin 6-3 6-3, but fourth seed Nadal needed three sets to beat Muller in their respective matches.
Nadal took out the first set comfortably, but had to settle for a 6-2 2-6 6-4 victory against a spirited Muller.
Tsonga beat Millot 7-5 6-1, while 11th seed Dominic Thiem also won in straight sets, while Josh Isner defeated Andreas Seppi 7-6 (7-1) 6-4.
PAIRE, KLIZAN AND DIMITROV MAKE EARLY EXITS
Just three seeds exited the tournament on Sunday as Paire was joined by Martin Klizan and Grigor Dimitrov in bidding an early goodbye to California.
Paire was outclassed by Adrian Mannarino 6-1 6-3 in just over an hour.
Klizan was forced to retire against former world number eight Fernando Verdasco after falling behind 5-3 in the first set. Verdasco will now take on Nadal, who he knocked out of the Australian Open in January, in the third round.
Dimitrov lost 6-4 3-6 7-5 to Alexander Zverev as the 18-year-old German continued to show his promise with a courageous fighting display.
It goes without saying that if you want to be Djokovic, you have to take your chances.
Fratangelo did just that in his first set performance, when he pounced on the Serb's sloppy start and took two out of three break point opportunities.
In the third and deciding set, he spurned three of four opportunities. A tough lesson for the 22-year-old.
That rule might not apply if you serve as well as Thiem. He only took one of 11 break point opportunities but sent down 10 aces on his way to a 7-6 (7-4) 7-6 (7-3) win.
ZVEREV STAYS COOL IN CALIFORNIA HEAT
"I tried to stay as calm as I could," Zverev said after beating Dimitrov. "Grigor played well for an hour or so, from the middle of the second set until the middle of the third. He didn't give me many chances, but I knew I would get my opportunities. And I used them well."
Djokovic, on the other hand, struggled through his win, saying: "All credit to Bjorn on playing a great match, but I wasn't feeling comfortable at all on the court.
"I was just trying to find a way, trying to hang in there and make it through."
SEEDS MEET AS ROUND THREE BEGINS
Second seed Andy Murray and third seed Stan Wawrinka will be expected to win comfortable against unseeded opponents Federico Delbonis and Andrey Kuznetsov respectively, but there will be tighter matchups elsewhere.
Unseeded young gun Borna Coric will be looking to prove his worth against Tomas Berdych, while Bernard Tomic (17) meets Milos Raonic (12) and Richard Gasquet (8) takes on Alexandr Dolgopolov (26).