Mark Cavendish dislocated his right shoulder and suffered ligament damage after crashing near the end of the Tour de France’s opening stage in Yorkshire.
The Briton collided with Simon Gerrans during the sprint finish in Harrogate, which was won by Marcel Kittel.
Cavendish was due to have an MRI scan with a decision on whether he will continue racing made on Sunday morning.
“It was my fault, I’ll apologise to Simon. I tried to find a gap that was not there, I wanted to win,” he said.
“I felt really strong and was in a great position to contest the sprint thanks to the unbelievable efforts of my team. Sorry to all the fans that came out to support – it was truly incredible.”
German Kittel raced clear to win the stage from Slovakia’s Peter Sagan and Lithuania’s Ramunas Navardauskas.
However, the vast majority of the thousands of people lining the finishing straight in Harrogate were focused on Omega Pharma – Quick-Step rider Cavendish.
The 29-year-old Manxman spent several minutes on the floor before being helped back on to his bike and he gingerly rode over the finish line.
He had been among the favourites to win the stage, which would have seen him wear the leader’s yellow jersey for the first time.
“It’s an unfortunate way to end what could have been a dream scenario,” said Team Sky boss Sir Dave Brailsford who has worked with Cavendish both on the road and track in his former role as head of British Cycling.
“He’s a great champion and he’s done an awful lot for this country. He’s one of the best cyclists we’ve ever produced, he’s given us great moments of pleasure and I’m sure he’ll get better soon.”
The Grand Depart was held in Yorkshire for the first time with more than one million fans estimated to have attended stage one. Police say 230,000 people were in Leeds and 10,000 more were on one of the climbs at Buttertubs.
When told there was one million people lining the route, Brailsford added: “It looked like more to me. It was just incredible, fantastic. I’ve never seen so many people in my life. The amount of people was unreal. It’s amazing that cycling can attract so many people.”
After a ceremonial start at Harewood House, which saw the Duchess of Cambridge cut the ribbon, the race headed out into the Yorkshire Dales, reaching the northern-most point in its 111-year history in the village of Reeth.
Veteran Jens Voigt, racing in his 17th and final Tour at the age of 42, led a breakaway from the start.
Initially it was a three-man attack with French duo Benoit Jarrier and Nicolas Edet, but German Voigt broke clear on his own after an intermediate sprint in Newbiggin and at one stage held a five-minute advantage over the 195 other riders in the race.
He was eventually reeled in by the peloton with 60km (37 miles) to go in the 190.5km opener.
The race geared up for a hotly contested sprint but Swiss Fabian Cancellara, who is more renowned as a one-day specialist rider, caused confusion when he launched a solo bid with 1km to go.
The sprinters reacted and heading into the final straight, Cavendish, who has won 25 Tour stages, collided with Orica GreenEdge’s Australia rider Gerrans and both of them crashed to the ground.
Team Sky’s Chris Froome, who is the defending champion, finished safely in sixth place. Team-mate Geraint Thomas was 17th, with the fourth Briton Simon Yates 61st, all four seconds behind Giant-Shimano’s Kittel.
Brailsford said: “The first stage of the Tour is about getting through unscathed; Froomey finished sixth. Job completed.”
For Kittel, it was a fifth stage win and a repeat of last year’s opening stage that he won in Corsica. He said: “I am incredibly proud of this victory.
“It happened pretty easily. It was like coming out of a tunnel. I was able to accelerate like never before. It’s really awesome. Deja vu, yeah.”
Sunday’s second stage takes the riders 201km from York to Sheffield and features around 3,000m of climbing, spread across nine categorised ascents.
Stage one result:
1. Marcel Kittel (Ger/Giant-Shimano) 4hrs 44mins 07secs
2. Peter Sagan (Svk/Cannondale) Same time
3. Ramunas Navardauskas (Lit/Garmin-Sharp)
4. Bryan Coquard (Fra/Europcar)
5. Michael Rogers (Aus/Tinkoff-Saxo)
6. Chris Froome (GB/Team Sky)
7. Alexander Kristoff (Nor/Katusha)
8. Sep Vanmarcke (Bel/Belkin)
9. Jose Joaquin Rojas (Spa/Movistar)
10. Michael Albasini (Swi/Orica GreenEdge)