There are many players going into 2020 on a roll, but John Isner is in a group of ATP Tour stars who need to bounce back quickly.
The ATP Tour is full of rising prospects and established stars who capture the attention of fans throughout the twists and turns of a calendar year.
Others, though, slowly but surely begin to slide down the rankings and struggle to establish momentum.
These are players who are still ranked highly enough to qualify automatically for almost every significant event, but are unable to get a meaningful run of wins together.
Doing that is difficult enough when you are out of form and even harder when your opponents are still the cream of the crop.
Usually it is a combination of poor performances, injury problems and bad luck in tournament draws that starts a decline, but often it is a pattern which is hard to reverse.
Still, those who did struggle this year will see the 2020 ATP Tour as their chance to bounce back.
We have picked out 5 notable players who saw their ranking drop in 2019 and are now under pressure to get off to a fast start to revive their fortunes when the new season begins.
The big-serving American was excellent in 2018, reaching the semi-finals of Wimbledon, the last eight of the US Open and winning the Miami Open, his first Masters 1000 title. All of that helped John Isner to a career-high ranking of number eight.
But in 2019 he struggled to defend those ranking points amid struggles with a serious foot injury. A defeat to Roger Federer as he tried to hold on to his Miami title was one of only two finals he reached.
And despite his injury woes largely explaining his drop in the rankings, Isner would not have been happy with his results at the Grand Slams either.
His best performance was the third round at Flushing Meadows, with early exits at the Australian Open and Wimbledon coming either side of his injury, which was suffered in that Miami final against Federer and stopped him from competing at the French Open.
Still ranked at 19 in the world, Isner has a platform to bounce back in the 2020 Slams, but given he turns 35 in April, he will know those big results must come quickly if he is to secure another major run.
Japan’s Kei Nishikori was another player who dropped out of the top 10 in 2019.
The former US Open finalist made three Grand Slam quarter-finals, though could not add to his three career major semi-final appearances. The biggest disappointment was a third-round Flushing Meadows exit against Alex de Minaur.
Nishikori’s only title of the year was at the Brisbane International, so he has points to defend early on in 2020.
Turning 30 this month, Nishikori is under threat of being crowded out by the ascendant younger generation.
Canadian Milos Raonic fell from number 18 to 31 over the course of 2019 and could drop further if he does not perform well in Melbourne next month.
The ex-Wimbledon finalist was well placed at the Australian Open before losing to Lucas Pouille in the last eight, with his year getting worse from there.
He did not play the French Open or US Open due to knee and glute injuries respectively, while he fell in round four in England after losing an epic match against Guido Pella. He later missed Canada’s impressive Davis Cup Finals run due to a back injury.
Since making the Wimbledon final in July 2016, Raonic has only made three ATP Tour finals, all of which were at ATP 250 level.
It is fair to say the pressure is on, which Raonic acknowledged in an interview with Sportsnet.
“I’m feeling good, I’m getting better, but it’s been a tough season for me,” he said.
“[Getting back to the top] is what motivates me. I think I’m a much better tennis player today than I was in 2016. I just have to find a way to give myself and my body the freedom to compete, the freedom to go on court and focus strictly on my tennis.”
Former US Open champion Marin Cilic was the world number 6 in October 2018 but is now down at 39 after a year that saw him go out before the quarter-final stage in each of the four majors.
After 11 consecutive years making at least one ATP Tour final, Cilic did not reach any in 2019, not a positive trend for a 31-year-old who has previously mixed it with the very best.
It looked like Great Britain had their next big tennis hope when Kyle Edmund ended 2018 up at number 14 in the world.
Twelve months later, he sits at 69 after a year to forget that saw him produce a 2-4 match record across the four majors, failing to get past the second round at any of them.
Still 24, it is far too soon to close the book on Edmund and his performances at the Davis Cup to conclude the year hinted at a revival.
But last year’s struggles are an undoubted concern and instead it is compatriot Andy Murray’s return that will be in the spotlight at the start of 2020.