The pair have two stage wins each from the first five and Sagan had predicted on Tuesday the Colombian might struggle with the climbs.
France's Yoann Offredo rides breakaway during the seventh stage of the Tour de France cycling race over 231 kilometers (143.5 miles) with start in Fougeres and finish in Chartres, France, France, Friday, July 13, 2018.
It was a first stage win of this Tour for Groenewegen and the second of his career after victory on the final day in Paris a year ago.
Greg Van Avermaet (BMC Racing) retained the yellow jersey and now holds a lead of six seconds over Geraint Thomas (Team Sky) after picking up a three-second time bonus.
Last year's third place finisher Romain Bardet has finished 31 seconds behind stage victor Dan Martin after swapping bikes with a team-mate following a mechanical problem.
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"A lot of people didn't believe in me anymore and thought I wouldn't come back to the same level". "I said I needed some time, and I didn't feel good in the first stages. I was going from a good position and the legs were good so it was a ideal day". The four-time Tour victor, aiming for a fourth successive Grand Tour victory, went straight on at a bend entering the eighth cobbled sector but recovered to finish in the main group. After the relatively flat first nine days, the race will head south and into the Alps and then the Pyrenees Mountains.
"I had a good day", said the Slovak, who has, like Gaviria, two stage wins so far.
"I tried to win the stage, but it was pretty complicated", Van Avermaet said. "I don't know what happened - maybe adrenaline - but I wasn't going to let anyone beat me".
Bardet was already trailing Froome, and after losing 28 seconds is now 1:45 off the leader's pace after he broke his back wheel and had to change bikes with Tony Gallopin.
Dumoulin, the time trial world champion and 2017 Giro d'Italia victor, was slowed by a tire puncture at the foot of the final ascent and lost 53 seconds. While Porte headed for hospital, their likely Plan B Tejay Van Garderen - who started the day just nine seconds off yellow - got himself caught up in crashes and conceded more nearly six minutes to effectively rule himself out of contention.