In the most recent Test at Headingley, Root scored his third century of the series as England won the game by an innings and 76 runs.
And that knock was enough to see him rise above Williamson to number one in the ICC’s Test batting rankings.
At the start of the series, Root was ranked number five, but his consistent run scoring has seen him return to the top of the rankings for the first time in almost six years.
Philip Brown/Popperfoto/Popperfoto via Getty Images)
Speaking ahead of the fourth Test at The Oval, Root said: “It [going to number one in the rankings] is a nice thing to hear.
“My main focus is on trying to keep scoring runs and get us across the line in this series. As nice as it is, there’s still so much hard work to do and the focus doesn’t change.
“It’s all about continuing to try and keep getting better, continue scoring runs and hopefully setting up games to win Test matches.
“It’s obviously nice but it’s not something I have as a goal or a main focus in what I’m trying to do, but I’m obviously proud to hear that I’ve achieved that.
“It would be nice to be able to stay there now and continue playing in the way I am.”
Australian batsman Steve Smith remains third in the latest set of rankings, ahead of his compatriot Marnus Labuschagne.
Rohit Sharma, meanwhile, has moved up to number five after scoring 230 runs at an average of 46.00 against England.
Sharma has overtaken his captain Virat Kohli, who has dropped to number six after scoring just 124 runs at an average of 24.80 against England.
Rishabh Pant has also fallen down the rankings, slipping out of the top ten and down to 12th after making just 87 runs in the ongoing series.
James Anderson has re-entered the top five in the ICC’s Test bowling rankings after his impressive display at Headingley, leapfrogging New Zealand ‘s Neil Wagner.
Jasprit Bumrah has also risen to number ten, overtaking Stuart Broad who is currently out of action with a calf injury.