Frenchman Victor Perez shot a five-under-par 67 to take a one-stroke lead after the first round of the season-ending World Tour Championship.
England's Tommy Fleetwood made the best start of the leading contenders for the Race to Dubai title on the European Tour.
Fleetwood, who is No.2 in the Race to Dubai rankings behind Patrick Reed, rolled in a birdie at the last hole for a 69 and was two shots behind Perez at Jumeirah Golf Estates.
Reed also birdied the 18th after an approach to four feet and had a bogey-free 70.
The fight to be crowned Europe's No.1 golfer in the 2020 season is wide open, with any of the leading 60 players in the standings mathematically in with a chance of becoming champion because there are so many points at stake in Dubai.
"The position I'm in, I have nothing to lose. I have everything to gain. So for me, it's a 'going for it' mentality to keep for the four rounds." – Victor Perez
Perez started the week at No.6 in the standings and his impressive first round, during which he made long birdie putts on the 11th, 14th and 17th, leaves him as the projected No.1.
His birdie at the 14th came from off the green, Perez using his 3-wood to roll the ball up the slope and down into the cup.
"The position I'm in, I have nothing to lose," Perez said. "I have everything to gain. So for me, it's a 'going for it' mentality to keep for the four rounds."
Matt Fitzpatrick, Robert MacIntyre and Erik van Rooyen were tied for second place after 68s.
Fleetwood, the Race to Dubai champion from 2017, was in a four-way tie for fifth.
Collin Morikawa, the US PGA Championship winner, was at even par.
He is third in the standings and, like Reed, looking to become the first American to win what was formally known as the Order of Merit title on the European Tour.