Froome and the other main contenders were more than seven minutes back when Trentin crossed the line in Lyon to become the first Italian to win a stage this year.
Froome managed not to lose any more time to his main rival Alberto Contador ahead of Sunday's daunting 21-kilometre ascent of Mont Ventoux — one of cycling's toughest climbs, where Britain's Tom Simpson collapsed and died during the 1967 Tour.
"I'm concentrating on the GC (overall classification), but of course it would be great to win tomorrow," Froome said. "In cycling terms it would be like a dream come true."
Froome, the Tour favourite, lost more than a minute to Contador, the two-time former champion, and Dutchman Bauke Mollema in Friday's incident-packed sprint stage.
This time, he thanked his teammates for keeping him out of danger on the 191-kilometre leg from the winemaking town of Saint-Pourcain-sur-Sioule in central France to the east-central city of Lyon, one of the gourmet capitals of France and home to the seven-time French football champion.
"My teammates controlled the stage and did a great job," Froome said. "Just keeping an eye on things."
Froome remains 2:28 ahead of Mollema, considered an outsider, and 2:45 clear of Contador, the 2007 and '09 champion who was stripped of his 2010 title for doping.
"A lot of people have reason to attack now," Froome said. "A lot of people spent energy in the last couple of days, so it will be an interesting one."
Ryder Hesjedal of Victoria is the top Canadian in 55th place. David Veilleux of Cap-Rouge, Que., is 137th, while Svein Tuft of Langley, B.C., is 178th.
Meanwhile, Trentin was overjoyed with his first stage win in a major race.
"I knew that if I started from 200 metres I could win," he said. "For sure a win in the Tour, this means something. I want to enjoy this because the next days are going to be hard."
As they contested the sprint outside Stade Gerland football stadium,Trentin surged from the back to beat Swiss rider Michael Albasini by half a wheel. American Andrew Talansky was third.
It was the second straight stage win — and third in the last four — for the Omega Pharma QuickStep team after Mark Cavendish won on Friday and Tony Martin clinched Wednesday's time trial.
"To be part of this team is incredible," Trentin said. "When I won the stage all my teammates came to say 'Congratulations.'"
The first three were followed seven minutes 17 seconds later by the heaving mass of riders in the peloton, with Froome's Sky and Alberto Contador's Saxo-Tinkoff teams forming a shield around their star riders.
An 18-man breakaway set off early, with Jens Voigt, Jan Bakelants and British rider David Millar driving it hard to get Garmin-Sharp teammate Talansky — the group's highest-placed rider in the general classification — in a good position.
Voigt's first Tour was in 1998 and Saturday's was his 303rd day of racing in the showcase race in his 16th Tour.
"To be honest, five years too many," Voigt said when asked why he couldn't last. "I'm 41, that's nature."
The yellow jersey group was about five minutes behind when the front-runners had all completed the second Category 3 climb. Those two were the biggest ones of the day but only moderate ascents compared to what awaits the riders on Sunday.
Millar calls the Ventoux climb "horrible" and Polish rider Michal Kwiatkowski is dreading it.
"It's such a legendary mountain that I'm a little bit scared about it," said Kwiatkowski, seventh overall but nearly five minutes behind Froome.
Sunday is Bastille Day. Judging by the thousands of people who turned out on the roadside to cheer on Saturday, the atmosphere up Ventoux promises to be electric.
Froome's Sky teammates have clearly struggled in two stages so far — in the Pyrenees in Stage 9 and Friday's flat stage — and he needs them to be at their best to repel any attacks from Contador so he can relax on Monday's rest day — the second of the race.
"My focus is going to be on keeping yellow, preserving the advantage I have," Froome said.