Rider security at the Tour de France was near to meltdown after the sponsors of Vincenzo Nibali, who crashed out of the race after colliding with a spectator, confirmed they were considering legal action against the race promoters, ASO, and liquid was thrown at Chris Froome.

Froome again bore the brunt of spectator abuse, 48 hours after the bad-tempered stage to Alpe d’Huez in which the Team Sky rider was shoved and spat at, and the 2014 Tour winner Nibali was downed by an errant spectator and forced to abandon the race with fractured vertebra.

Initially the indication was that Nibali’s team, Bahrain-Merida, had accepted the incident was simply bad luck; but the team manager, Brent Copeland, has now confirmed legal action is possible and that he is warning his riders to steer clear of Froome.“In the past we said, ‘Guys, stay up front to avoid the crashes.’ Now we say: ‘Don’t stay behind Froome, it’s dangerous,’” Copeland said.

The security concerns that have dogged this Tour since the race start in the Vendée two weeks ago have now become a major headache for the race organisers. Froome, whose presence on the race became intensely controversial after ASO sought to ban him from competing, before clearing him to race, has been the focal point for most hostility.

On Saturday there was further hostility with what appeared to be beer thrown at the four-times Tour winner and further booing and jeering towards the finish of the stage. “I’m not surprised,” his teammate and race leader, Geraint Thomas, said. “We’ve had a bit of that. It’s always been water from what I’ve seen. But I wouldn’t know what it was [today].”

Copeland added that “Froome’s facing the risk of something happening every day. Chris told me that himself when we spoke recently. The other day on Alpe d’Huez, Vincenzo was behind Froome after he’d attacked. Chris managed to avoid the motorbikes and everything. Vincenzo went down.”

As for Nibali’s crash and subsequent abandonment, Copeland said his team had “suffered huge damage” and the team’s lawyers were exploring possible legal action.

“The fans invaded the road and the gendarmerie didn’t do what they should,” he said. “They also didn’t do anything about the people lighting flares. It’s not easy to control more than 600,000 fans as there were the other day but as they’re so powerful and so well organised, some things have to be managed firmly.”

The tensions around Froome and Thomas appeared to lessen briefly on the winding wooded roads of the Ardèche and Lozère as an uneventful 14th stage climaxed with a breakaway victory for Omar Fraile of Spain, the first Tour stage win of his career.

Fraile was home, hosed and celebrating well before the group of favourites began the steep final climb to Mende aerodrome. It took a speculative move from the unheralded Slovenian rider Primoz Roglic to light any fires, with Tom Dumoulin trying his hand 2km from the finish, but Thomas and Froome were able to respond as they closed on the airstrip finish overlooking Mende.

Yet even on the 3km ascent to the aerodrome there was some damage inflicted. Adam Yates, who had hopes of a revival in the latter stages of the race, was among the first to crack while Romain Bardet and Mikel Landa were unable to keep pace with Thomas, Dumoulin and Froome, now firmly established as the three favourites for final victory in Paris.

“It was a tough little final,” Froome said, “only a 3km climb, but explosive, tough. I think we saw the damage it did, even a short climb like that.

“There were gaps opening up all over the place and a few seconds gained here and there with a few guys. All in all we are pretty happy with myself and Geraint, up front. Dumoulin seems to be our biggest threat.”

Once again it was Thomas who appeared the most comfortable of the three favourites, with Froome being briefly dropped. “The goal was always to ride into this Tour and I think I timed it well,” Froome said. “I had a good block of recovery after the Giro and building up, into the Tour, was definitely the right thing to do for me.”

Thomas also cited Dumoulin, the Giro champion in 2017, as the greatest threat to Sky’s hold on the race lead. “It’s impressive,” he said of the Dutchman’s performance. “He can really pace himself well.

“He’s the world time-trial champion and he knows exactly how to ride whether its a 3km climb or Alpe d’Huez. You don’t know if he’s really suffering or just pacing himself. Fair play to him. It takes some balls to do that, especially when you have no teammates, but we’re just happy to be in the situation we are.”