Rory McIlroy insists his best years are yet to come as he prepares to defend his title at The Players Championship.

McIlroy will this weekend attempt to defend the title he won in 2019 for a second time, with last year's tournament having been called off after the first round due to the coronavirus pandemic.

The Northern Irishman started the 2020 event with a 72, leaving him nine shots adrift of leader Hideki Matsuyama and facing a battle to hold onto the trophy.

That performance was in stark contrast to his form leading up to last year, when he arrived at TPC Sawgrass as world number one after top-five finishes in each of his first four tournaments of 2020.

McIlroy found it a comparative struggle after golf restarted from its three-month break, and he endured a frustrating weekend at the Arnold Palmer Invitational, following an opening 66 with rounds of 71, 72 and 76 to finish eight shots behind winner Bryson DeChambeau.

Given the 31-year-old has not won any of golf's majors since 2014, it was put to him that the best years of his career could now be behind him, but that is something he disputes.

He told reporters on Tuesday: "I've talked about this before: you have to be an eternal optimist in this game, and I truly believe that my best days are ahead of me, and you have to believe that.

"There's no point in me being out here if I didn't think that. That's just not part of my psyche or anyone's psyche out here. I think that's the difference between people that make it to the elite level and the people that don't, because they don't think that way. I certainly believe that my best days are ahead of me, and I'm working hard to make sure that they are.

"It felt so good on Thursday and then felt off a little bit on the weekend, so it's like, what happened? What changed? What is the difference? I think that's where I've sort of struggled the last few weeks is that inconsistency of the good being very good, good enough to lead the golf tournament, but when it just gets slightly off, not being able to manage it.

"There's inconsistency in my ball-striking from day-to-day. On my approach play on Thursday, I gained nearly three shots on the field, and then Saturday I lost nearly three. It's just the inconsistency. It's not being able to manage the misses as well as I usually do.

"The good golf is in there, and I feel capable of going out and shooting good scores any week that I play on any golf course that I play, but it's the days where you don't feel so good that you need to manage it and get it around in a couple under par. That's the challenge for me right now."

McIlroy accepts he will likely find this weekend's challenge more difficult than two years ago, but he remains confident he can challenge.

"I feel like I can go out there this week and string four good rounds together, but it's maybe just a bit more of a challenge than it maybe felt a couple years ago," he added.

"But that's on me to try to get a little more comfortable and work pretty hard these next couple of days to be ready to go on Thursday and feel like I'm in a bit of a better place with it all."