Simona Halep looked every inch the world number one as she rode out a rocky WTA Finals opener against Caroline Garcia to win in straight sets.

Garcia's late run to Singapore came courtesy of an 11-match winning streak that included titles in Wuhan and Beijing, the latter sealed with a final victory over Halep.

But the Romanian took this contest 6-4 6-2, showing a greater fluency in the crucial exchanges to start her quest to hold off six rivals for her top ranking in style.

Though Garcia's purple patch came to an end, she impressed on her debut at the tournament and may fancy her chances against Red Group rivals Elina Svitolina, who she beat in Beijing, and Caroline Wozniacki.

The Frenchwoman pushed Halep all the way in the 2017 French Open finalist's first service game, but the top seed clung on in a 16-point slog that lasted almost 10 minutes.

Garcia conceded a solitary point in her opening two service games, but Halep came alive in the next, creaming a backhand winner up the line before a pair of wild Garcia backhands sealed the break.

Halep double-faulted on break point in the next game to lose the initiative, but game nine featured some brilliant tennis, Halep shaping cross-court but going up the line to hoodwink Garcia, whose efforts to force deuce were for nothing when she too double-faulted at the crucial moment.

And Halep saw out the set immediately, sending a laser-guided backhand up the line to move ahead. 

After scrapping out the first set, Halep clicked into top gear in the second, sending Garcia across the baseline at will to break in game three and then fighting back from 0-40 down each time to win the next two games and prompt chants of "Si-mo-na, Si-mo-na!" from an excitable crowd littered with Romanian flags.

Garcia looked defeated and the loss was brought up when she whipped an easy winner into the tramlines, but on this evidence she could still enjoy success this week.

STATISTICAL BREAKDOWN
Halep [1] bt Garcia [8] 6-4 6-2

WINNERS/UNFORCED ERRORS
Halep – 13/11
Garcia – 13/16

ACES/DOUBLE FAULTS
Halep – 4/3
Garcia – 0/3

BREAK POINTS WON
Halep – 4/5
Garcia – 1/6

FIRST SERVE PERCENTAGE
Halep – 62
Garcia – 61

PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Halep – 62/71
Garcia – 58/43

TOTAL POINTS
Halep – 67
Garcia – 50