Nitto ATP Finals 2019: Dominic Thiem's chances of winning the title 

For 26-year-old Dominic Thiem, the year of 2019 has been sensational. Initially apprehensive about his consistency on every surface, Thiem has gone on to defeat Rafael Nadal, Novak Djokovic as well as Roger Federer in the last few months.

It has been a particularly productive year for the Austrian as he has added five titles to his trophy cabinet. Usually seen as a clay-court specialist and next-in-line after Rafa Nadal at the French Open, Thiem has unleashed a more rounded performance. Aside from collecting two clay-court titles, the 26-year-old has also taken home three more hard-court titles in 2019.

There are several things that are plurally responsible for the boost in the form of the Austrian. Perhaps the most noticeable change that has taken over Thiem's game has occurred after he took the major decision to part ways with his coach of 15 years, Gunter Bresnik.

Bresnik, who is also from Thiem's homeland has previously coached the likes of Boris Becker. Thiem's call for a change in the coaching hands came in February with former Olympian Champion, Nicolas Massu soon stepping in as an improved replacement. The Chilean coach helped Thiem reshape his game and soon enough, he got busy making it to one final after the other.

Ever since March, when Thiem went into the finals of the Indian Wells, nobody could have guessed that he would go on to defeat Roger Federer. By defeating the 20-time Grand Slam champion, Thiem bagged his first-ever ATP Masters 1000 title on any surface. Soon enough, Thiem was racing ahead to win two more titles on hard-court in Beijing and Vienna while Barcelona and Kitzbuhel became sites for his staple clay-court victories.

The massive highlight for Thiem this year is the change of coaching styles. Massu, being younger and more contemporary, can relate to Thiem's game more. Although the 2004 Athens Olympics Singles and Doubles medalist also prefers the clay court, he tasted success more on the faster courts. This fact has played a key role in Thiem's game as his style has changed and adapted better for the hard court game, where he is excelling currently.

Another big achievement for Thiem came during the French Open when the Austrian clashed with Novak Djokovic in the semi-finals of the Grand Slam. In an extremely long drawn out match that spanned over two days, peppered by 'hurricane'-like conditions on the Roland Garros soil, it was Thiem who crushed Djokovic's hopes ultimately.

Djokovic's shot at owning all four titles at the same time twice was shattered when Thiem emerged as the better player in the five-set thriller. With that, Thiem made it to his second consecutive French Open final and set up a usual clash with Rafael Nadal. However, Thiem could not ward off Nadal from claiming his 12th French Open title but the Austrian did triumph against the Spaniard in the semifinals of the Barcelona Open.

For Thiem, who would always consider the ATP Finals to be a hard thing to get into, this would be the fourth straight year for him. Thiem gained early entry into this year's Race To London list after he defeated the young Greek, Stefanos Tsitsipas in the finals at Beijing. Initially unsure of his ability to get so many points on the board and play so consistently throughout the year, Thiem has slowly gotten better at his game and is a strong threat for the Big Three.

In his previous three appearances at the London O2 Arena, Thiem has not been able to progress beyond the Round Robin matches. He has always had to settle for a single victory before exiting the tournament. Drawn in the Bjorn Borg group this time, Thiem has six-time Champion, Roger Federer, five-time Champion, Novak Djokovic and London debutant Matteo Berrettini as his opponents during the group stage matches.

Thiem will begin his bid for a rare shot at the ATP Finals trophy on Sunday against Roger Federer. Leading the way in the head to head against the Swiss legend at 4-2, Thiem will come into the match slightly confident of his past record.

Truth be told, Thiem isn't the strongest candidate when it comes to bagging the trophy at the ATP Finals. But the World No.5 player, in his fourth outing at the O2 Arena, can pack us in for a surprise. Under the guidance of his new coach, Thiem can produce a different quality of tennis and be a threat to his group members.

With this new and focussed version of Thiem, it would be safe to say that we should steady ourselves for surprise wins and upsets as he takes to the court on Sunday night.