Racing got one over Muster on Sunday when they won the crucial European Cup match 34-30.
They got their first European match win at the brand new U Arena but Muster did get their crucial bonus point for losing within 7 points.This kept them at the top of pool 4 for now.
Machenaud finished the game with 20 points which put them one point behind Munster on the log.
This will put some extra pressure on next week pool stages which will be and exciting weekend of rugby.
Both sides score tries in the first half with Machenaud boot the difference which gave Racing a 13-7 lead at the break.
The missed penalties by Murray and Keatley proved to be very costly for Munster.
Racing got over in the corner in the second half through Andreu but a great try by Earls saw Munster pull back the score to 18-14.
Farrell try gave Munster the lead but some penalties from both sides saw the lead exchange several times in the second half.
Racing then struck a big blow, when Thomas set up Szarzewski to put them in a 28-17 lead.
A huge penalty by Murray was followed by three points by Machenaud as he clinched a dramatic win with another late kick.
Munster will end up at a guarantee top spot if they beat Castre next week with a bonus point.
Racing will play Leicester must better must better Munster’s result or face the perils of the best runners-up calculator.
For Racing 92:
Tries: Nyanga, Andreu, Szarzewski
Cons: Machenaud 2
Pens: Machenaud 5
Tries: Kleyn, Earls, Farrell
Cons: Keatley 3
Pens: Keatley 2, Murray