(REUTERS) - Top golfers need to pick up their games to keep pace with Dustin Johnson, Australian Jason Day said on Sunday after losing top ranking to the long-hitting American.
After 47 consecutive weeks at the top, Day ceded his position when Johnson won the Genesis Open on Sunday.
Johnson had knocked on the door before, spending much of 2016 as world No. 2, before making another push at the start of 2017 and finally passing Day.
"Whatever he's doing, he just needs to keep doing it," Day told reporters after finishing a distant equal-64th at Riviera.
"If he keeps playing the way he's playing, we've got to pick our game up and try to compete with him."
Another ex-world No. 1, Adam Scott, advised Johnson to enjoy his new status while it lasts.
"Just enjoy it, because as we've seen since Tiger (Woods) really dominated that position, no one's staying there too long," said Scott, who was top of the rankings for 11 weeks in 2014.
"The target's on your back and everyone's coming for you. There just isn't the separation between the top players that there was during that long period of time when Tiger was far ahead."
Woods, who is struggling to mount a comeback after major back surgery, was ranked No. 1 for a record 683 weeks in total, including a record 281 consecutive weeks between June 2005 and October 2010.
Another former No. 1, Jordan Spieth, said it was no surprise that Johnson had kicked on since his major breakthrough at last year's US Open.
"Once that happened, that was a big monkey off his back mentally, and it frees him up," said Spieth, who headed the rankings for 26 weeks in 2015.
"He was given a hard time for a long time about close calls in majors."
Spieth was the beneficiary of one of those close calls, at the 2015 US Open, when Johnson missed a three-foot putt that would have forced a play-off.
Johnson also failed to close the deal in several other majors, but his rivals feared it was only a matter of time before he learned to win the most important tournaments, and the 2016 US Open victory proved them right.
"He's just one of those natural-born golfers," said 2013 US Open champion Justin Rose.