Johnson moved to the head of the field in the delayed second round on Saturday, shooting a second successive round of 66 to sit a stroke clear on 10 under par.

He was unable to start his third round on Saturday evening as bad light suspended play at 5.43pm CST - 17 minutes before Johnson was due to return to the course.

Day managed five holes of his third round and a bogey on the 11th - his second - dropped him to a tie for 53rd, nine shots back on Johnson.

Play was suspended for most of Friday and a further rain delay on the morning of day three pushed back the schedule at Riviera Country Club even further.

But once the action resumed Johnson took charge, starting with a birdie on the first and adding further gains on the fourth, 15th, 17th and 18th.

Johnson told Sky Sports: "We've got two more rounds to go so we'll see what happens.

"I want to win this tournament. Whether I get to number one or not doesn't really affect me. I want to put myself in a position to have a chance in the final round."

If Johnson hangs on for victory, Day will have to produce something special to keep hold of his ranking.

PGATOUR: Adam Scott.
Dustin Johnson.

Let's look at two of the best hit driver.

Take notes. ✏️ pic.twitter.com/v89Ba5561F

— 🌴Carolina Petes🌴 (@carolinapetes) February 19, 2017

The Australian completed his second round by matching his one-under score from his first go but he dropped back to one-under par overall before the light faded.

Japan's Hideki Matsuyama also started the week with hopes of topping the rankings but he will play no further part in California after making nine bogeys and missing the cut.

American duo Pat Perez and Cameron Tringale lie a shot behind Johnson, with the latter having chipped in on the 18th to record a seven-under 64 in the second round.

England's Luke Donald and world number six Jordan Spieth are well placed to make a charge in the final two rounds, sitting four and five shots back respectively.

Play will resume at 6.50am local time on Sunday morning.