Nash leads the league with 10.1 assists per game with Rondo second at 9.4.
That point guard matchup is unlikely to take place, however, since Rondo left Wednesday's 96-73 win over Toronto late in the third quarter with a right wrist injury after a flagrant foul by Linas Kleiza. Coach Doc Rivers said Thursday it is unlikely that Rondo will play.
The Celtics (5-8) will face a challenge to slow down the 37-year-old Nash, averaging 15.1 points and shooting 55.2 percent.
"You can see, you watch Steve play, I don't see where he's missed the beat," coach Alvin Gentry said. "I think he's playing as well as he did when he was MVP of the league. He's the guy that we count on to do almost everything for us offensively."
Rivers compared Nash to legendary boxer Muhammad Ali.
"With Nash you don't know what he is," Rivers told the Celtics' official website. "You don't know if he's a score-first, you don't know if he's a pass-first. He's almost like ... he reminds me of Ali. Every fight, is he going to do the rope-a-dope? Is he dancing? I mean, you don't know what he's doing."
If Rondo does not play, second-year guard Avery Bradley or rookie E'Twaun Moore will start.
These perennial contenders have fallen on hard times, enduring uncharacteristically long skids heading into play Wednesday. They ended them by taking advantage of similarly struggling teams.
Boston got 21 points from Rondo for its first victory since Jan. 4.
Phoenix (5-9), meanwhile, won for the first time since Jan. 8 with Wednesday's 91-88 victory at New York. Nash had 26 points and 11 assists against his former coach, Mike D'Antoni, and the Knicks.
"Right now, we could have beat anybody and it'd be sweet," Nash said. "It's been a tough year, we've had a tough stretch, so for us, any win is a huge relief and hopefully will give us some confidence and maybe get us going a little bit."
Nash and the 39-year-old Grant Hill are the elder statesmen of the Phoenix lineup. The 25-year-old Rondo is the only regular Celtics starter under 33.
The age has been a factor on offense. The Celtics average 90.2 points for one of the NBA's lowest marks while the Suns are in the middle of the pack at 93.9 after being in the top five in each of the previous seven seasons since Nash rejoined the club.
"I can't put my finger on the fact that we're struggling to get to 100 every game," Gentry said. "I thought that would be one of the areas where we'd have the least worries and it's become just the opposite."
These clubs split two meetings last season. Boston's Kevin Garnett averaged 23.0 points on 70.4 percent shooting and 10.0 boards while Phoenix's Marcin Gortat averaged 16.0 and 15.0.