Britain's yellow jersey holder Chris Froome, of Team Sky, came over the finish line with the main peloton and his chief rivals just over seven minutes adrift.
Froome did not come under attack during the undulating 191km ride from Saint-Pourcain-sur-Sioule to Lyon and still leads Dutchman Bauke Mollema (Belkin) by 2min 28sec and Spain's former two-time winner Alberto Contador (Saxo) by 2:45.
A day after Froome and several leading challengers lost 1:09 to key rivals Contador and Mollema, the contenders for overall victory kept their powder dry ahead of Sunday's first summit finish at Mont Ventoux.
After a frenetic start to the stage, during which a number of attacks were launched and countered, a group of 18 riders finally broke free of the main bunch and went on to build a healthy lead.
Cracks in their collaboration began to appear, however, around 20km from the finish.
With two of the day's seven small climbs still to negotiate, Frenchman Julien Simon tried his hand and came over the summit of the 1.8km Duchere climb with a 20sec lead.
However the Sojasun rider's hopes of becoming France's first stage winner on this edition ended when he was caught by Albasini just outside the final kilometre.
Attacks by veteran Jens Voigt (RadioShack) and German Simon Geschke (Argos) came to nothing, and just as Albasini began powering towards the finish, Trentin opened up his sprint to come over the line half a wheel's length ahead of the Orica rider.
Trentin's win means Omega-Pharma now have four stage wins following victories by sprinter Mark Cavendish (two) and time trialist Tony Martin.