ATP Finals: Can anyone topple Novak Djokovic and Roger Federer?

The ATP Finals starts in London on Sunday and the two players have dominated the talk in the build-up to the season-ending event.

New world number one Novak Djokovic and 20-time Grand Slam champion Roger Federer are among the players at the O2 in the event dubbed the 'Major Fifth'.

Djokovic and Federer were joined by Alexander Zverev, Kevin Anderson, Marin Cilic and Dominic Thiem in qualifying for the tournament after finishing in the top eight of the rankings.

Kei Nishikori and John Isner, meanwhile, made the cut after the injured Rafael Nadal and Juan Martin del Potro were forced to withdraw.

VERDICT

As one of the most highly-rated young players in the world, Zverev is no stranger to hype.

The 21-year-old has been described as a great Slam winner for the past two years and is quickly catching up with the likes of Nishikori and Thiem for the number of career titles won.

Perhaps it is about the weather in Germany. Considering his ability and form in ATP Tour events, it is a surprise that he has only reached the quarter-finals of a major ounce, at the French.

His moment at the Slams will undoubtedly come to a goal in this week, against the sport's elite.

Having reached the semi-finals in Shanghai and Basel just last month, Zverev then made the quarter-finals of the Paris Masters where he lost to eventual champion Karen Khachanov.

On the face of it, Zverev should be feeling optimistic about a promising runs at the O2, but it's a good idea to have a good time.

MARIN CILIC

VERDICT

At the age of 30, Cilic has seen and done it all. Aside from Federer and Djokovic, he is the most experienced, respected and accomplished player in the line-up.

And yet Cilic and the ATP Finals is a combination that rarely produces success.

In three appearances at the season-ending tournament, the Croat giant has managed to win just one of his nine matches, suffering defeats to the likes of Andy Murray, Tomas Berdych and Jack Sock. Will this be a factor this week? Perhaps.

But a more legitimate concern is Cilic's overall form. Since reaching the quarter-finals at Flushing Meadows, he has endured a difficult period, losing five of his eight matches.

He took a set Djokovic in Paris but only seemed to be in the Serbian great, who proceeded to win the match in fine style.

The draw seems to have been worked out in the past, at least, and to the best of its ability, especially if it is hampered by injury and the dangerous but is flawed Isner.

JOHN ISNER

VERDICT

While Rafael Nadal's withdrawal was a significant blow to the tournament and the Spaniard himself, it has at least opened the door to Isner.

The big-serving American Nadal was confirmed in the first year of the year.

Known for his mammoth serve, which has produced almost 11,000 aces, Isner has shown in his races at Wimbledon and the US Open.

During his career, Isner has won 92% of his service and will be able to meet his expectations.

The 33-year-old would naturally be incredibly difficult to break and he certainly could snatch a couple of surprise victories in tie-breaks.

Isner's problem is that he finds himself outclassed when coming up against fellow top players and some of the best returners in the game will be standing on the other side of the court in London.

Group Lleyton Hewitt

KEVIN ANDERSON

VERDICT

No player in this year's line-up has won less titles in their career than Anderson, but that does not mean the South African should be discounted.

In fact, there is enough evidence to suggest.

The late bloomer from Johannesburg, reaching for two Grand Slam finals and securing victories over the likes of Federer and Andy Murray.

Beating Federer at this year's Wimbledon was particularly impressive.

He was thrashed by Djokovic in a late one-sided final, but this was more likely to happen after his marathon semi-final meeting with Isner.

Anderson possesses one of the finest serves in the sport goal, crucially, has proven to have the overall game to trouble anyone.

DOMINIC THIEM

VERDICT

Often described as a clay-court specialist, Thiem is determined to show more than one pony trick.

Having reached back-to-back semi-finals at the French Open, Thiem went on this year, finishing as runners-up as Rafael Nadal won his 11th title at the venue.

Despite being a Grand Slam champion, the 25-year-old has been disappointed on hard, indoor courts.

But perhaps, recent results show Thiem is finally about fulfilling his true potential and announcing himself as a great all-rounder player.

Flushing Meadows had not been a happy hunting ground for the Austrian but he enjoyed a promising run to the quarter-finals this year.

A shock defeat of Nadal appeared to be on the cards after Thiem took the opening set 6-0, but the then-world number one rallied to win in five sets.

Still, Thiem's ​​performance in New York – and his subsequent victory in St. Petersburg – suggest he is ready to raise his favorite clay-court season.

KEI NISHIKORI

VERDICT

Nishikori surprisingly represents the player with the most experience in ATP Finals events, having played in three tournaments and reaching the semi-finals on his last appearance in 2016.

Despite only participating in the event because of Juan Martin del Potro's withdrawal, the Japanese sensation is arguably the favorite to progress from this group along with Federer.

To qualify for the tournament is impressive in itself, with the US Open finalist enduring a disastrous start to the year he was knocked out of a challenge by Dennis Novikov.

Nishikori was plagued by injury problems at the start of the year but made the quarter-finals of Wimbledon and beat Marin Cilic on his way to a semi-final US Open.

He is able to compete in the field of football in Paris and Shanghai. He is capable of competing with the best.