The hosts' third straight win moved them above Brive -- losers at Stade Francais -- and denied Montpellier the chance to significantly cut the gap on leaders Clermont, who lost 26-20 at Toulouse
In-form Pau halted depleted Montpellier's title momentum and dragged themselves away from the soft underbelly of France's Top 14 on Saturday with a 32-27 win.
The hosts' third straight win moved them above Brive -- losers at Stade Francais -- and denied Montpellier the chance to significantly cut the gap on leaders Clermont, who lost 26-20 at Toulouse.
Some 12,000 fans braved frosty conditions to see southwestern rivals Pau and Montpellier engage in a hard-fought encounter featuring seven tries -- five in a first half in which Pau emerged with a wafer-thin 22-20 lead.
After an early Demetri Catrakilis penalty for Montpellier, Watisoni Votu went over on five minutes before Louis Dupichot pulled out two further scores. Two Tom Taylor conversions and a penalty before the break kept up the momentum.
But Pierre Spies, back at number eight as one of nine changes, and Yvan Watremez kept Montpellier -- missing a dozen men through injury or suspension -- in the hunt with tries in quick succession for the visitors which South African fly half Catrakilis converted.
A James Coughlan try just before the hour with Taylor, in fine kicking form this season, landing the conversion and then another penalty held off spirited Montpellier resistance as Duhan Van der Merwe's try eight minutes from the end converted by Francois Steyn proved just insufficient.
"We built on the two good wins over Clermont and Bordeaux in beating Montpellier," said Pau skipper Julien Pierre. "They didn't come here to celebrate New Year and this is an important win."
Watremez was sanguine at the narrow loss, which was no doubt softened further when Clermont lost later in the day and now have a four-point lead at the top over Montpellier.
"We came here to win but we knew it would be difficult. Today is a loss. We get a bonus point but we can't be satisfied with that. We'll keep working and hope to get off to a good start in the New Year."
In other games Stade Francais narrowly edged out Brive 12-10 and Castres hammered Bayonne 47-18 on a good day for the home sides.
On Friday Lyon ended a four-match losing streak with a 19-16 win over Bordeaux.
The result allowed Lyon, who will move to the Stade Gerland, the former home of the city's football club, in January, to go 10 points clear of Grenoble, who occupy the first of the two relegation spots, and 12 clear of rock-bottom Bayonne.
Third place La Rochelle host Grenoble on Sunday and Toulon host the team just a point below them in Racing 92.