Wellington - Gael Monfils became the third big name to pull out of the ATP Tour's Auckland Classic on Monday sidelined by injury while seventh seed Denis Shapovalov was bundled out in three sets.
Monfils, the eighth seed, said he was hampered by a niggling pain in the leg.
His withdrawal followed the absence of top seeds Tomas Berdych and Roberto Bautista-Agut, who both pulled out after contesting the Qatar Open final on Saturday which Bautista Agut won 6-4, 3-6, 6-3.
The flamboyant Monfils said his injury flared up on Saturday and had not responded to treatment.
"I have had a pain for two days with my quadriceps and unfortunately I am not able to play the tournament," he said.
"So I'm disappointed about the situation I've put myself and the tournament through, because obviously this year is tough because they've had a couple of retirements."
Shapovalov, the 19-year-old Canadian and only seed in action on day one, romped through the first set against Portugal's Joao Sousa, but went off the boil for most of the second set.
The third set went with serve until 3-3 when Sousa made the vital break and then held on to win the error-filled match.
"The first tournament of the year is not easy," Sousa said of the below par performance.
"For sure it was not his best day, me neither, but this is tennis, you try your best with what you have and I made it."
In the reshuffled draw, John Isner takes over as top seed and goes straight through to the second round to play fellow American Taylor Fritz.
Fritz, who opened with a 4-6, 6-3, 6-4 win over Romanian Marius Copil 4-6, 6-3, 6-4, has lost his two previous matches against Isner.
Germany's Philipp Kohlschreiber continued his phenomenal run in Auckland when the 35-year-old defeated American Bradley Klahn 6-4, 7-6 (7/2) to move through to the second round for the 11th time in 12 years.
In other action, German Jan-Lennard Struff won his first set 7-6 (7/5) against Laslo Djere and led 2-0 in the second when the Serbian retired.
Tennys Sandgren raced through his opening singles 6-3, 6-4 against qualifier Mackenzie McDonald and will face third seed Marco Cecchinato in round two.