World champion Mark Cavendish won Friday's stage in a sprint finish, while Joaquin Rodriguez retained the overall lead, 17 seconds ahead of Hesjedal.
The Spaniard will wear the pink jersey for the fourth successive day on Saturday.
Hesjedal, who finished with the peloton Friday to remain second overall, wore it for three consecutive days, making history as the first Canadian to earn the pink jersey.
The stage win marked the third of the year for Cavendish, who finished in a time of three hours two minutes and seven seconds on the shortest leg of the race, a 120-kilometre ride from Savona to Cervere.
The Briton appeared boxed in on the approach to the line but managed to squeeze past former teammate Matt Goss for the win.
Alexander Kristoff was second and Mark Renshaw third. The Australian Goss finished sixth.
The route was mainly downhill apart from a short climb at the beginning. There was an early breakaway as Martijn Keizer and Francesco Failli created a gap of four minutes 15 kilometres into the day. The gap eventually increased to more than five minutes before the peloton started reeling it in.
Team Sky and Greenedge took to the front as the peloton cycled into the final 2.5-kilometre home straight, preparing to give Cavendish and Goss the best possible chances.
Cavendish then left his team behind and held off attacks from other sprinters as he forced his way through, bursting clear just 100 metres from the line and winning by a bike length for his 10th Giro stage win of his career.
The race moves to the Alps next, with the 14th stage covering 204 kilometres from Cherasco to Cervinia.
The Giro ends on May 27 in Milan.
— With files from The Canadian Press.Suggest a correction