Novak Djokovic is back at No.1 and still has plenty of room for improvement, according to the Game Insight Group.

Novak Djokovic regained the world No. 1 ranking on Monday, having climbed from outside the top 20 at the start of the year.

And the worrying thing for his opponents? He might have only just got started.

Djokovic’s climb back to No. 1 has taken in two Grand Slam titles and a 47-10 win record, leading to a total improvement in his Elo rating* from the start of the year of +265.

NEWS: Nishikori beats erratic Federer in London

Elo ratings are an alternative to more traditional rankings aimed at giving a greater insight into a player’s performance ability.

As impressive as that ratings climb is, it isn’t unprecedented, especially when you consider players who are just coming onto the scene and have the most room to improve over a short period of time.

If we limit past improvements to players that were in a similar situation to Djokovic at the start of this year – i.e. players who have been playing professionally for several years and who began the season at an already high rating (1800+) – then the list becomes much shorter.

Only four other men in Open era history have had a similar rise at an already mature stage of their career.

Thomas Muster’s 1988 performance takes the first spot, a year when he rose from outside the top 50 to a ranking of 16, gaining nearly 300 Elo rating points along the way.

Player Year Highest Elo improvement 1. Thomas Muster 1988 +298 2. Paradorn Srichaphan 2002 +296 3. Novak Djokovic 2018 +295** 3. Joachim Johansson 2005 +276 5. Pat Rafter 1997 +276

Djokovic’s +295** improvement gets an asterisk because there is still time for him to go even further based on his results at the Tour Finals.

When we put Djokovic’s 2018 rise in relation to his two best seasons, 2011 and 2015, we see that his current season high is still far from his peak potential. In fact, Djokovic is only now around a level that was on par with his strength at the start of 2011 (at a rating of ~2100).

So, even while Djokovic is back at No. 1, if his peak performance is still an achievable goal, he could be even stronger than his current rating suggests.

That has to be a frightening prospect for the field but an exciting one for tennis fans looking towards the 2019 season.

*How do Elo ratings work?

Elo ratings are already used in many other sports and when applied to tennis they outperform other published prediction methods, including those based on offical rankings.

Elo ratings factor in all main draw singles matches above the Challenger level.

Elo is smart about how many points are won or lost. If a player did more than expected in earning a win against a strong opponent, they earn more points than for an easy win. If a player underperformed by getting upset, they lose more points than for losing to an equal opponent.

Elo ratings can be surface-adjusted, taking into account all of a player’s matches, but weighing those on the specific surface more heavily.

Elo ratings of players absent from competition for more than three months are deducted 100 points. Walkovers and retirements are excluded.

Players earn/lose more points for results over the same opponents at Grand Slams compared to lower-level tournaments.

Read the full article at Stats On The T.