It was a marathon day at waterlogged Riviera Country Club, but when the final putt dropped Dustin Johnson was atop both the leaderboard and the world rankings. Here’s how things ended up at the Genesis Open, where Johnson won by five shots:

Leaderboard: Dustin Johnson (-17), Thomas Pieters (-12), Scott Brown (-12), Justin Rose(-11), Wesley Bryan (-11), Kevin Na (-11), Charley Hoffman (-11)

What it means: Johnson started the morning with a lead, but he put the tournament out of reach with a third-round 64 that built his advantage to six shots. It allowed him to cruise to the finish line while challenging the tournament scoring record until a pair of back-nine bogeys. The victory vaults Johnson to No. 1 in the Official World Golf Rankings for the first time in his career and extends his streak to 10 straight seasons with at least one PGA Tour win.

Round of the day: Pieters had a Hazeltine flashback during the final round, channeling his masterful Ryder Cup performance en route to a closing 8-under 63. The Belgian had four birdies on each nine and failed to drop a shot, a performance that gave him his best finish in just his seventh career start on Tour.

Best of the rest: Martin Laird began his final round with an eagle on No. 1 and kept it going from there, carding a 5-under 66 that vaulted the Scot into a tie for eighth for his fourth top-10 finish of the young season. Laird made four birdies from Nos. 9-17 and would have finished even higher in the standings were it not for a 72nd-hole bogey.

Biggest disappointment: Jason Day didn’t put up much of a fight as Johnson took the top spot in the OWGR away from him. The Aussie shot rounds of 75-71 during Sunday’s marathon, dropping into a tie for 64th after he failed to break 70 in any round in L.A. despite the soft conditions.

Quote of the day: “It gives me a lot of confidence. It’s going to push me to work even harder, try to get even better.” – Johnson on becoming No. 1.