The evolution of Patty Mills from a towel-waving bench warmer to a key cog in the San Antonio Spurs machine was clear in two plays in their latest NBA Finals win.

The plays weren't among his four successful three-pointers.

They came when the 183cm, 84kg point guard from Canberra found himself defending one-on-one the world's best basketballer, the Miami Heat's LeBron James.

It was a mismatch on any terms.

The 203cm, 113kg multiple MVP James often devours such chances, but in Thursday's game four of the NBA Finals, with James desperate to get his team a home-court win and level the series, it was Mills who won both duels.

"I didn't really see a mismatch in my eyes," Mills said after the Spurs' 107-86 win, giving his team a 3-1 lead and putting them just one win away from the NBA Championship.

"When you come up against someone like that, that's the mindset you have to have."

After the win, Mills's team-mates showered him with praise.

He is known as an offensive threat, but Spurs veteran Manu Ginobili affectionately described Mills as a defensive "pest".

When Mills heard Ginobili's description he offered a smile: "On the court or off the court?

"I think that's a good word to describe my job because that's what I have to do."

If the Spurs defeat the Heat on Monday, Mills and his Queensland teammate Aron Baynes will join Luc Longley and Andrew Gaze as Aussie NBA Championship ring winners.

Spurs head coach Gregg Popovich said without Mills he would not have been able to rest his starting point guard Tony Parker during the marathon regular season and playoffs.

Parker has battled leg injuries after playing four years without a break, his summers devoted to duties with the French national team in European, Olympic or world tournaments.

At the start of the season Popovich needed a reliable back-up point guard and it came down to Mills or Canadian-born Cory Joseph.

"When Patty came to camp this year all trim, very aggressive, very focused he made us notice him and that he wanted to be part of this and didn't want to be on the bench," Popovich said.

Popovich found himself leaving Mills on the court and Parker on the bench.

Parker won't play for France at the World Cup in Spain in August-September, but Mills will lead the Boomers.

"I wish luck for Patty this summer because I'll be on vacation all summer," Parker said.

"I'll be laughing at Patty next year." - AAP