Westbrook scored 18 points, Daequan Cook hit four 3-pointers in quick succession to help Oklahoma City pull away in the first half and the Thunder led wire to wire in a 107-97 victory over the Phoenix Suns on Saturday night.
The Thunder are perfect in four New Year's Eve home games that have become a tradition since the franchise moved from Seattle to Oklahoma City.
"You've got to start the new year with a win," Westbrook said. "Hopefully, we can keep this going."
At 5-0, Oklahoma City is also off to the franchise's best start since it won the first six games of the 1998-99 season -- the last time the NBA schedule was shortened because of a lockout.
Behind the strong start has been a lockdown defense that has held each of the first five opponents to under 45 percent shooting. The Suns made 39.8 percent, becoming the third opponent to make less than 40 percent.
It's the first time in 30 years Oklahoma City's franchise has held three of its first five opponents under 40 percent from the field.
"We're playing hard, everybody's engaging on the defensive end and helping each other," said Thabo Sefolosha, who scored 12 points. "It's a big part of our success right now."
Two nights after his buzzer-beater against Dallas, Kevin Durant had only 12 points in his bid to become the first player since Michael Jordan a quarter-century earlier to score at least 30 in the first five games of a season.
"We have not been able to do a lot of the stuff that we anticipated doing," coach Alvin Gentry said before the game. "Obviously, we've got some of the core guys but you're talking about second-unit guys and things like that. We haven't been able to do nearly as much as we would like to.
"From a playbook standpoint, we've probably put a third in as opposed to what we would have done in a normal situation."
Oklahoma City led from the outset, getting a two-handed dunk from Serge Ibaka just after the opening tip and scoring the first seven points. The lead grew to 17-5 after Westbrook's steal and two-handed breakaway dunk just over 5 1/2 minutes in.
That was the only time it would be close.
Nick Collison hit a runner at the other end, and Oklahoma City's reserves started to take over after the quarter break. Cook hit four 3-pointers in a 5-minute span and Collison and Nazr Mohammed both had two-handed slams during a 22-6 push that extended the lead to 54-35.
The Thunder led by 14 at halftime, despite only two first-half points from Durant, and only let Phoenix get closer than that a couple times in the final 5 minutes, when both teams had reserves playing in garbage time.
Durant's 3-pointer with 5.5 seconds left in the third quarter bumped Oklahoma City's edge to 89-67. At that point, Phoenix was shooting just 37 percent and had missed 18 of its 22 shots from 3-point range.
"Their guys made shots early and we did not. I think we are very inconsistent on offense right now, and I guess that just comes with trust and time," Frye said. "We have to grind it out. We do it some nights, and we need something to rely on, which I think should be our defense (to) give us more opportunities on offense."
The Thunder's starters remained on the bench throughout the final period as everyone got to play.
Lazar Hayward, picked up in a preseason trade with Minnesota, and first-round pick Reggie Jackson each got their first playing time of the season. Hayward scored his first points with Oklahoma City on a right-handed, fast-break dunk.
Jackson got his first pro bucket on a baseline drive for a layup.
The Suns managed to improve on their NBA-worst 24 percent shooting from behind the arc only by making all four of their 3-point tries in the fourth quarter.
Phoenix was fourth in the NBA last season by making 38 percent of its 3-pointers.
"We wanted to get back. That was our first thing that we talked about: Get back in transition defense so we can match up with their big guy that's rolling and all their shooters on the perimeter," Thunder coach Scott Brooks said.
"They're a high-volume 3-point shooting team and that was a big part of our strategy tonight: Make sure we get back and cover their shooters."
Cook didn't play in the second half because of flulike symptoms and finished with 12 points. Collison added 11 and James Harden had 10 points and matched his career high with eight assists for Oklahoma City.
"We don't have very much in, to be honest with you. What we're trying to do is we're trying to become real efficient in what we have in and if we become really efficient with that, then we can move on to something else," Gentry said.
"We can't have 20 extra things in and not do any of them good. So, we're very limited in what we're doing."
Gentry complimented Durant for making a "phenomenal" game-winning buzzer-beater two nights earlier but also said "those guys did a really good job of getting him open, even if it was an illegal screen." Video replays showed Kendrick Perkins and Harden both set moving screens to get Durant open. Brooks only chuckled and said, "Both picks were good."... The Thunder's previous New Year's Eve wins were against Golden State in 2008, Utah in 2009 and Atlanta in 2010. ... Hinder guitarist Mark Long played the national anthem.