Williamson expects 'phenomenal' Root to keep breaking records
New Zealand begin a South Asia tour against Afghanistan in a one-off Test near New Delhi on Monday, ahead of two Tests in Sri Lanka and three more in India.
Williamson is one of the current generation of leading Test batsmen alongside Root, Virat Kohli of India and Australia's Steve Smith, who were dubbed the "Fab Four" by late New Zealand great Martin Crowe.
"(Root) has been phenomenal, and I'm obviously a big fan of his," 34-year-old Williamson told reporters at the Greater Noida ground on Saturday, venue for the Afghanistan clash.
"I've enjoyed watching not just him, but obviously those other guys," he said, referring to Kohli and Smith.
He called all three "amazing players" that have "moved the game forward in a big way".
Root has been among the runs lately, in contrast to the dipping form of Kohli and Smith.
The former England captain Root has been in blazing form in recent weeks, scoring three centuries and three fifties in five home Tests, including hundreds in both innings against Sri Lanka at Lord's.
Root scored his 34th Test century in the process to go past Alastair Cook's previous England record of 33 tons, and now stands in seventh spot on the list of the all-time run-scorers with 12,390 runs.
India batting great Sachin Tendulkar tops the chart with 15,921 runs and 51 centuries in a glittering 200-Test career which ended in 2013.
Williamson said Root, who is only 33 years old and has played 146 Tests, has the potential to surpass Tendulkar.
"There is a lot of attention on what he might achieve in the years to come," he said.
New Zealand will be playing their first Test for six months when they take on Afghanistan, but Williamson said he felt confident.
"Playing for my country, for my team, makes me perform on the field," he said, adding he was "very excited" to play six away Tests which will count towards the World Test Championship.
"In some ways, it's like a tournament sport, even though it's over a long period", he said.