Late winner for Toulon over Racing
The match, opposing two sides packed with international talent, came two weeks before they are due to face-off again in the European Champions Cup quarterfinals.
Both sides scored two tries with Frederic Michalak nailing the winning penalty kick for Toulon with the last action of the match.
"We could have scored two more tries in the first half but we had the luck and the desire," said Toulon coach Bernard Laporte.
"When we conceded a try two minutes from the end of the game [to take the score to 18-20] I thought that's a pity as we deserved to win and we wouldn't have been rewarded."
But Laporte refused to read too much into the victory, two weeks out from their European clash.
"We can't take too many conclusions. Today was one league game in 26. In Europe, it's a different context - it's a knockout."
Toulon now have 61 points, just one point behind leaders Clermont who have a tough trip to Bordeaux on Sunday.
Racing slipped back to fourth place after two straight losses and following a 45-21 romp for Montpellier at rock-bottom Agen.
"We could have won the match in the last minute but on the whole I don't know whether it would have been deserved," said Racing coach Laurent Labit.
"We lost too many balls and you can't do that against a team of assassins like Toulon."
Michalak, making his first start since France's World Cup quarterfinal thrashing to New Zealand in October, and Dan Carter, playing at centre for the home side, had an early exchange of penalties before Toulon scored the opening try of the game.
Racing were pressing just short of the Toulon tryline only for hooker Jean-Charles Orioli to intercept. He fed wing Delon Armitage, who sprinted clear and held off a late challenge to touch down in the corner.
Michalak made it 11-3 with another penalty before Racing enjoyed a long period of sustained pressure, from which they were unable to add to their score before half-time.
They were made to pay the price for that lack of a cutting edge 10 minutes into the second half with another piece of opportunism from Toulon.
No.8 Charles Ollivon was quickest to pounce on a loose ball at a maul allowing him to break through the middle past two tackles.
He offloaded to centre Theo Belan who ran in unopposed for his side's second try. Michalak converted to make it 18-3 to the visitors.
Carter popped over his second penalty on the hour and with six minutes to go Racing finally managed a try, flank Wenceslas Lauret barging his way over through two covering tackles.
At 18-13 down Racing needed a converted try to pull off an unlikely win, and they thought they had got that with three minutes to go, scrum-half Maxime Machenaud breaking clear to feed inside to Carter.
But from the kick-off replacement prop Martin Castrogiovanni was collared for obstruction and Michalak slotted home the winning kick from 35 metres out.
Montpellier are third, just a point behind Toulon, after a six-try romp past Agen for a fifth win in five matches.
Jake White's Montpellier had trounced a second-string Racing 60-7 last week and despite leading just 10-7 at the interval on Saturday they raced to victory in the second half.
South African compatriots Francois Steyn at centre and flank Pierre Spies started a Montpellier game together for the first time and Spies marked the occasion with his team's first try after six minutes.
Springbok hooker Bismarck du Plessis grabbed a brace of tries with another South African, flanker Wiaan Liebenberg also on the scoresheet.
Fijian wing Timoci Nagusa scored the other two.
Agence France-Presse