It was the first five-set victory of his career for Saulnier, 56th in the ATP Champions Race, but it will be a defeat that will be extremely difficult for Rusedski to digest.
Fellow Brit Alex Bogdanovic, a late qualifier for the event, turned things around to lead 2-1 against Spain's Alex Calatrava after losing the first set but then won just five games in the final two sets to lose 6-3, 3-6, 4-6, 6-1, 6-4.
"It was tough out there. I'm really disappointed to lose a tough five-set match," said Bogdanovic.
"But I've had a great week and I've got to take all the positives out of it. To qualify for my first Grand Slam, it feels great."
Tim Henman hopes to defy the odds once again when he begins his campaign today.
Henman's form has nose-dived since his unexpected appearance in the French Open semi-finals in May.
And a tough draw, which starts against 6ft 10in Croatian Ivo Karlovic today, has done nothing to help his chances. Henman said: "Since I arrived here a week ago practice has gone really well.
"It has been good to hook back up with (coach) Paul Annacone again and the time we have spent on court has been very worthwhile."
Andre Agassi breezed into the second round with a 7-6, 6-4, 6-2 victory over fellow- American Robby Ginepri.
The 21-year-old, 13 years younger than Agassi, took the the sixth seed to a tie-break in the opening set, forcing him to fight back from 4-1 and 5-3 down before failing in the decider.
Agassi, who won his first tournament in 16 months at Cincinnati three weeks ago, also overcame a break in the second set.
Fellow veteran and former Davis Cup team-mate Todd Martin announced his retirement after a 4-6, 6-4, 6-4, 7-5 loss to Fabrice Santoro of France.
Top-seed Roger Federer, who won the Australian Open and Wimbledon this year, defeated 2002 French Open champion Albert Costa 7-5, 6-2, 6-4 to reach the second round.
Third-seed Carlos Moya of Spain beat American wild card Brian Baker 6-7, 6-4, 6-4, 6-2.
Olympic silver medallist Mardy Fish knocked out Spain's David Ferrer in straight sets 7-5, 6-3, 6-2.
