Rory McIlroy was denied another "euphoric moment" in becoming World No.1 for the first time since September 2015 and admits he faces a tough task to stay at the summit.
McIlroy and Brooks Koepka did not contest last week's AT&T Pebble Beach Pro-Am, but McIlroy moved above the American due to the vagaries of the two-year rolling ranking system.
Both are in action at this week's Genesis Invitational, where former US Open champion Webb Simpson is the only member of the world's top-10 not competing in a star-studded event hosted by Tiger Woods at Riviera Country Club.
This is McIlroy's 96th week in total as World No.1, one behind the record for a European player held by Sir Nick Faldo, although his lead over fellow four-time Major winner Koepka is just 0.03 points.
"Everyone keeps saying congratulations but the work's only started, it's staying there is the hard part," McIlroy told a pre-tournament press conference.
"It's a calculation based on how you've played the last two years and I've played consistently well, and the mathematics add up that I'm top of the list right now and I have a chance to stay there this week.
"I've always said it's a by-product of doing the right things week in, week out, playing well, trying to win tournaments, and if I can continue to do that then hopefully that thing takes care of itself."
Asked if it was something of an anti-climax to become No.1 during a week off, McIlroy added: "I've already that euphoric moment in 2012; I won the Honda Classic to get to No.1 in the world, Tiger was coming down the stretch, I was able to hold him off. That to me was the really cool moment.
"At least I've had one of them, that's nice. To me it doesn't matter if I was sitting at home on the couch and got there or whatever, it is what it is.
"So I've already had that experience and I think as long as you do get that experience, especially the first time you get there, that's all you need."
Meanwhile, the PGA Tour Series-China has postponed four tournaments and two qualifying events because of concerns over the spread of the coronavirus.
The qualifying tournaments were scheduled for Bintan in Indonesia and Phuket in Thailand, with the event in Bintan having already been switched from Haikou in China.
It is hoped that the qualifiers can be played in late April or early May, with the regular season beginning in late May or early June.
The postponed tournaments are the Sanya Championship (March 23-29), the Haikou Classic (March 30-April 5), the Chongqing Championship (April 6-12) and the Guangzhou Open (April 13-19).
"We watched and scrutinised the situation closely and we did not make this decision lightly," PGA Tour Series-China executive director Greg Carlson said.
"After consultation with a variety of agencies, we determined postponement of the qualifying tournaments and the start of the regular season are the best courses of action at this time.
"This is a major international health issue, and we will do everything possible to ensure the safety and well-being of our players and everybody else associated with these two tournaments.
"We appreciate the patience our players have shown during what is a difficult time as they try to prepare for their seasons. At the same time, we don't want to do anything that might jeopardise the health of them or anybody else who is involved in PGA Tour Series-China."
Earlier this week, LPGA tournaments in Thailand and Singapore were cancelled due to the ongoing situation.
The Honda LPGA Thailand, which was scheduled to take place from February 20-23 in Pattaya, and the HSBC Women's World Championship - due to be held in Singapore from February 27-March 1 - were called off.