ATP World Tour Finals 2016 Results: Sunday Tennis Scores and Updated Schedule

Novak Djokovic beat Dominic Thiem in his first match at the 2016 ATP World Tour finals, but only after being pushed to a third set at London's O2 Arena on Sunday.  

Djokovic lost an epic tiebreak in the first, before delivering a shutout in the second. The third set decisively turned the Serb's way when he broke Thiem's serve for the fourth time to close out a 6-7(10), 6-0, 6-2 win. Djokovic has now gotten his bid to reclaim the world No. 1 ranking from Andy Murray off to the right start.

Based on this form, the Serb has to be favoured to win the Ivan Lendl group and qualify for the semi-final stage.

Later on Sunday, Milos Raonic leaped to the top of the standings in the Ivan Lendl after dominating Gael Monfils 6-3, 6-4 in what turned out to be a fairly one-sided affair at the O2.

Here are the scores and results from Sunday's matches:

Player	Score	Player
Novak Djokovic	6-7(10), 6-0, 6-2	Dominic Thiem
Milos Raonic	6-3, 6-4	Gael Monfils

All scoring and schedule information per the ATP World Tour's official website.

Monday's schedule is highlighted by Andy Murray's first time on court. The world No. 1 will face off against Marin Cilic after Stan Wawrinka meets fifth seed Kei Nishikori.

Recap

Impressive though Djokovic was, Raonic's performance lit up the Day 1 schedule with a straight-sets hammering of France's Monfils, who was ultimately way off the pace in his opening match of the competition.

Jose Morgado of Portuguese newspaper Record provided a breakdown of the standings in the Ivan Lendl group after the first day of the tournament came to a close:

Monfils won just 48 percent of all second serve points he played, according to Flashscore.com, although it was Raonic who tipped the balance in unforced errors, contributing 13 to his opponent's 10.

As noted by TENNIS magazine, this result at least made it clear Raonic is no longer struggling with injury after he was forced to withdraw from the Paris Masters semi-finals earlier in November:

The Canadian was particularly impressive at the O2 Arena on Sunday as he failed to surrender a single break of serve, not to mention he didn't allow Monfils to clinch any more than two points in any one of his serving games.

It's that kind of form that may just give the Canadian a chance against Djokovic in the Ivan Lendl group, and tennis writer Tom Tebbutt highlighted the Serb is most likely next on his schedule:

Djokovic was pushed into some brilliant tennis by his younger opponent. Thiem, still just 23, was holding serve and challenging the Serb with his own delivery.

He boomed a hat-trick through the first seven games. Jose Morgado of the Portuguese publication Record congratulated the youthful Austrian player on his service game:

However, Djokovic is a savvy enough all-rounder to adapt to any game. Thiem was challenging his move skills across court.

Yet the Serb was also moving his less experienced opponent into positions where he was less comfortable. In particular, Thiem struggled to defend the corners whenever Djokovic dragged him wide.

ATP strategist Craig O'Shannessy noted how Djokovic was moving Thiem around and which shots he was attacking:

Djokovic couldn't break Thiem's serve. But keeping his opponent on the move during his own service games was forcing the younger man into some costly errors.

Metro's George Bellshaw noted how the mistakes were piling up for Thiem in the opening set:

Yet it was Djokovic who soon had to save a break point after dragging a disappointing backhand into the net. The Serb held, but Thiem soon pushed him to a tiebreak when Djokovic did the same back on serve.

Djokovic just didn't seem his typically ruthless and efficient self. He'd been pushed to a tiebreak and squandered several opportunities to claim the set.

Thiem kept the pressure on in the tiebreak with some fantastic shots like this one, via ATP World Tour:

Eventually, Thiem won the marathon-length tiebreak 12-10 after five set points. He took the set and left Djokovic perturbed and rattled.

So Djokovic was in no mood to be denied at the start of the second set. He finally broke Thiem's serve and soon earned a double break for a three-game lead.

Thiem was clearly overwhelmed and never recovered, as Djokovic served up a bagel to take the second without dropping a game.

However, the Austrian was able to stop the rot by winning the first game of the third. A pair of strong forehands caused Djokovic problems in the next game, but he hung on to hold serve and level the set.

Julian Finney/Getty Images

Next, the second seed survived a cute drop shot from Thiem to earn what looked like a decisive break of serve and go 2-1 ahead. The pressure was now firmly on Thiem.

To his credit, he stayed in the match, trailing 3-2 before Djokovic went 4-2 ahead and then secured another significant break. Serving for the match, Djokovic made no mistake of victory.

Djokovic offered a reminder to Murray he's no spent force just yet. Meanwhile, Thiem showed why he's one to watch in the coming years.