Roger Federer and Rafael Nadal enter this week's Shanghai Masters bidding to unseat current champion Novak Djokovic, who appears on an unstoppable march to ending the year as number one for the third time.
"Incredible" was how the Serbian described his victory in the China Open final on Sunday, one of the most one-sided tennis finals of recent years.
"With this kind of performance, and with this domination result-wise, I mean it's never happened," Djokovic said after defeating world number six Tomas Berdych 6-0, 6-2.
The victory represented Djokovic's fifth consecutive Beijing title, and the 27-year-old is vying for his third in three years at the ATP World Tour Masters 1000 event in Shanghai.
"I'm going to try to use this great week to kind of carry this overall positive feeling into Shanghai and have another great week there," he said. (Also Read: Federer Could Overtake Nadal as No.2)
Hoping to derail Djokovic's plans are a resurgent Federer, along with Nadal, who is battling to be at his world-beating best after his return to action following three months on the sidelines.
The Spaniard, who is number two in the ATP rankings, missed a string of tournaments -- including the US Open -- after picking up a wrist injury in training in late July.
His return to competition at the China Open ended abruptly when he was dumped out of the tournament by Slovak qualifier Martin Klizan in the quarter-finals.
The 14-time Grand Slam winner is seeded second in Shanghai but was the first to criticise his performance -- and his mental state -- in Beijing.
"What affects this is when one player plays bad, plays without rhythm, no confidence on the shots, having more mistakes than usual, being not confident how to play the points, and how to win the points," he said.
- Federer regains confidence -
Federer, however, has enjoyed a remarkable return to form after a miserable 2013, when the 33-year-old claimed only one title, failed to make any Grand Slam finals and finished outside the top five for the first time in 11 years.
The third seed in Shanghai, he has won a record 17 Grand Slams and said he was better prepared mentally for the tournament this year following his turnaround on the court.
"Last year was a struggle throughout, especially starting in March last year all the way to, I'd say, about here," Federer said, explaining that he had been "missing practice sessions" and avoiding intensive training as he was "scared" of getting injured.
"All of that has gone away. Now I really can focus on just playing. I've been able to create a big base again of fitness, and also now confidence has come back. Now I can just go out and play."
Federer's best showing at the Masters 1000 event was as runner up in 2010, although he did win in Shanghai when it hosted the Tennis Masters Cup in 2006 and 2007.
The Swiss could overtake his great rival Nadal in the rankings in Shanghai, but both are some distance behind Djokovic.
Elsewhere, two-time Shanghai winner Andy Murray is desperately chasing points as he pushes to qualify for the ATP World Tour Finals, the end of season finale involving the top eight players.
The 27-year-old Scot is currently ninth in the race for the London tournament after winning the Shenzhen Open at the end of last month, but faces competition from the rising stars of tennis who will also be in Shanghai.
Among them are Japan's Kei Nishikori, who made history at the US Open when he became the first Asian to make a men's Grand Slam final, losing to Croatia's Marin Cilic.
Federer is due to open his Shanghai campaign against Argentine Leonardo Mayer or home-crowd favourite Wu Di, but faces a tough route to the final, potentially meeting Nishikori or Bulgaria's Grigor Dimitrov in the quarters.
The Shanghai Masters started on Sunday, but the top eight players receive byes to the second round, which gets under way on Tuesday.