Viviani made the most of a Deceuninck-Quick Step train, positioned at the front by Alaphilippe and formed of Argentina's Maximiliano Richeze and Denmark's Michael Mørkøv, to overtake Norway’s Alexander Kristoff of UAE Team Emirates and win a bunch sprint.

He completed the 213.5 kilometres route from Reims to Nancy in a time of 5 hours 9min 20sec.

Kristoff had to settle for second place, while Australia’s Caleb Ewan of Lotto Soudal came third.

Victory for Viviani completes his Grand Tour trilogy having previously won stages at the Giro d’Italia and Vuelta a España.

It comes a day after Alaphilippe prevailed on stage three, from Binche to Épernay.

"This victory means a lot to me," Viviani said. 

"I can’t believe it. 

"It was my biggest goal of the year. 

"I missed the first chance on stage one in Brussels, but after Julian won yesterday, it switched on the team. 

"My lead-out men Michael Morkov and Max Richeze did a perfect job. 

"I only had to finish it off in the last 180 metres."

Alaphilippe's overall time at the top of the general classification now stands at 14:41:39.

Belgium's Wout van Aert of Team Jumbo-Visma is 20 seconds behind in second place.

Team-mate Steven Kruijswijk of The Netherlands is a further five seconds off the pace in third.

Defending champion Geraint Thomas of Great Britain remains in seventh spot.

The Team Ineos rider is 45 seconds adrift.

Stage five is due to take place tomorrow.

It is a 175.5km route from Saint-Dié-des-Vosges to Colmar.

The 21-stage event is scheduled to conclude on July 28.