And though Van Avermaet's BMC squad pipped Sky to victory by four seconds - denying Thomas yellow by just three seconds - Sky did enough to put four-time victor Froome firmly back in the general classification mix.
Gaviria was left thrilled after his impressive stage win on his very first Tour de France, achieved after he outlasted world champion Sagan in a long struggle down an 800m home straight with Kittel, who won four stages on the 2017 Tour, leaving his bid too late and coming third.
Marcel Kittel, victor of five stages in last year's Tour, saw his hopes of contesting the sprint effectively ended by a flat rear tyre with 7.5km to go, but the bigger incident was still to come. Rigoberto Uran's EF Education First-Drapac team gave up 35 seconds in fifth, Mikel Landa and Nairo Quintana's Movistar 54 seconds in 10th, and Vincenzo Nibali's Bahrain-Merida team 66 seconds in 11th.
Overall, Froome is in 18th place, 55 seconds off the pace and still 44 behind 2017 Giro d'Italia victor Dutchman Tom Dumoulin, who with Team Sunweb only lost seven seconds to the Briton on Monday.More news: Jimmy Kimmel refutes Trump claim at S.C. rally: 'That never happened'
"It's amusing because at the end of the day it's just another bike race".
"Some days you're on the right side of it, others you lose time but proud of my boys today", the Irishman tweeted.
"It's reassuring to take back some time".
Porte's BMC team had been expected to make up for their disappointing first day when their Australian leader fell.More news: Being dead is a ‘breach of contract,’ PayPal tells grieving husband
Dan Martin wants to build on his sixth place in the 2017 Tour de France, but admits that the team time trial could make things more hard in 2018.
The World Anti-Doping Agency accepted Froome's explanation of the result, which essentially challenged the foundation of the test, showing that levels of excretion can vary widely as a result of factors such as dehydration. Smith was focussed on winning the climber's polka dot jersey, and once he had secured that after the only classified climb came early in the stage, he was called back to the bunch to help his team. I think there will be a lot more time lost throughout the GC group before we hit the mountains. That would have been a nice bonus on top.
Kiwi rider Patrick Bevin leads BMC Racing through the team time trial course on the Tour de France. We just wanted to get that stage.
His Etixx Quick-Step team-mates provided a ideal lead-out train and, despite the presence of sprinting royalty, Gaviria pulled away to become the first debutant to win the opening stage of the Tour in 14 years.
"We're happy, we had the yellow and that's part of history". The Kenyan-born British rider also crashed on the opening day of the Giro d'Italia in May, while warming up for the Stage 1 time trial.More news: Israel will not ‘rule out’ ties with Syrian govt - Defence minister