Brandon McNulty (UAE-Team Emirates) soloed to victory by over a minute at the Trofeo Calvia, the first elite .1 men's race of the year on Wednesday afternoon.
The American broke clear of a select group with 60km to go before the Coll den Claret, and then kept away from the chasers all the way to the finish in Palmanova.
His teammate Joel Suter came second, 1 minute 17 seconds behind, with Vincenzo Albanese of Eolo-Kometa in third after a sprint among the remains of the lead group.
McNulty originally attacked on the Coll den Blenda, 82km into the race, which helped break up the peloton, before he surged away again before the second ascent of the Coll den Claret.
He had 50 seconds of advantage at the top of that climb, and managed to increase that by the finish line, although it looked at times that he would be brought back.
The chasers, who also included Emanuel Buchmann (Bora-Hansgrohe) failed to organise their effort effectively.
Speaking after his victory, McNulty said that he knew it would be "tough to chase" on the unpredictable Mallorcan roads.
"I'm super happy, it's a great way to start the year," he said. "It was a tough day, but it was really good day for me, and the team as well, we came second. It was up and down all day, there was never really a flat road.
"As the group became smaller, I was able to establish a gap, and I knew if I could hold on it would be tough to chase, with the road the way it was, twisty and always up and down. I put an attack in and was able to hold on for the win, so I'm super happy."
It was the 23-year old's first win for UAE-Team Emirates, and only the third of his career after he won a stage at the overall of the Giro di Sicilia while racing for Rally in 2019.
Wellens, who finished fourth, acknowledged that McNulty was the strongest man on the day.
"We wanted to take the initiative with the team in the descent of the Coll de Sóller, which we did and there the race exploded," he explained.
"Afterwards, I was part of a breakaway with also McNulty, who went solo and took the win. There’s no arguing, he was the best man in the race. Back in the chasing group, we looked at each other and it was impossible to get away."
Meanwhile, Valverde was given the combativity award for his efforts on the day. This is the Spaniard's 21st and final season as a professional cyclist.
The Challenge Mallorca continues with four more individual one-day races over the next four days.
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