The opening stage of the Tour de France has been marred by several crashes, including a horror pileup caused by an oblivious spectator.

With just over 45 kilometres to go, the peloton passed through a narrow road following a short climb, where a spectator holding a sign stepped out onto the road to try and get on television.

The sign collected Jumbo-Visma rider Tony Martin, and caused a domino effect through the bunch, with riders either hitting the deck or being caught up behind the crash.

Because Martin was near the front of the peloton, only a handful of the 184 riders weren't impacted, with one rider, Jasha Sutterlin, having to abandon as a result of the pileup.

The inattentive fan was slammed by fans and riders alike on social media.

The riders who escaped unharmed waited for everyone impacted by the crash to rejoin the peloton, but disaster struck again with 7.5 kilometres to go, with a touch of wheels at high speed from a B&B Hotels rider causing another major crash, that saw riders fly off their bikes into a ditch.

The second crash caused a major shakeup in the overall race as well, with the surviving riders pushing on to the finish and leaving major contenders in their wake.

Amongst the big names to lose significant time was last-year's third place finisher Richie Porte, who lost two minutes and 16 seconds, while top climbers Miguel Angel Lopez (sixth last year) and Emanuel Buchmann (fourth in 2019) lost one minute and 49 seconds.

That crash saw two further riders have to abandon the race without completing a stage, and also had an impact on the finish to the stage, with the absence of several contenders and key teammates leaving a reduced group to battle it out.

Julian Alaphilippe, the charismatic world champion, took advantage, attacking on the steepest part of the final 3.2 kilometre climb, and impressively holding on to take victory by eight seconds, and claim the first yellow jersey.

Amongst a group of 20 riders eight seconds down were the two race favourites - the Slovenian duo of Tadej Pogacar and Primoz Roglic - with Roglic taking third place to snare four bonus seconds. Also in the group was former champion Geraint Thomas, while his teammate and fellow top contender Richard Carapaz arrived five seconds further back.

However, with many star riders crossing the line battered and bruised, the impacts of the two crashes - and one fan's actions - are likely to linger throughout the tour.