London - Chris Froome's biggest rival has turned his attention back to the Tour de France but the three-time champion does not regard Colombia's Nairo Quintana as his most dangerous threat.
Quintana, runner-up to the Briton in 2013 and 2015, made an audacious bid for a rare Giro d'Italia-Tour double this season, but after losing out to Tom Dumoulin in Italy, Team Sky's Froome believes the Movistar rider may have over-exerted himself.
"My biggest threats come from guys who did not do the Giro - Richie Porte, (two-time winner) Alberto Contador and (last year's runner-up) Romain Bardet," Froome, who also won the Tour in 2016, told Reuters in a telephone interview on Wednesday.
"I think it is going to be tough for Nairo to do the Giro and the Tour."
Quintana, who was third overall last year, looked nothing like the ruthless climber he built his reputation on in Italy, failing to make Dutchman Dumoulin, renowned more for his time-trial speed, crack in the mountains.
Although he did not see much of the race because he was at a training camp in Tenerife "where there was no TV", Froome said Quintana could have been cycling within himself in Italy.
"He may then be doing better on the Tour because he is a rider who is better in the second than the first grand tour," the Kenya-born 32-year-old said.
Froome, however, tipped former Australian team-mate Porte as a major contender.
"Richie has been amazing this season, winning the Tour Down Under and recently the Tour of Romandie. I think this year's Tour suits Richie really well," he explained.
Porte was Froome's lieutenant at Sky from 2012-15 before leaving for American outfit BMC to become a team leader.
"He's definitely got a chance to be up there for the win. This season he has been showing what he is capable of. I always believe in Richie," Froome added.
Porte, however, has a tendency to suffer from damaging bad days that can kill off his chances in the grand tours but he did claim his best result in one last year when he finished fifth in Paris.
Froome now relies on Geraint Thomas to guard him in the peloton and the Welshman can be expected to be in fine shape for France after he was forced to abandon the Giro early following an unfortunate crash.
"On the one hand, it was a huge setback for Geraint that he was not able to finish the Giro... but for the Tour, it will be only a good thing for the team because he will be fresher and have more time to prepare," the Briton added.
Froome has had a low-key season to date but will continue his preparations for his main targets against Spain's Contador and Frenchman Bardet at the eight-stage Criterium du Dauphine starting on Sunday.
"I think it has been a build-up similar to what I had last year. I think it worked well and I was able to do the Tour and the Vuelta (a Espana)," he said, adding that another attempt to win the Tour of Spain was "not confirmed".
"After the Tour, if everything goes well, I'd love to do the Vuelta," he added of a race he has finished second in three times.
One of his biggest challenges on the Tour, however, will be to keep a cool head under what have often been difficult circumstances for Team Sky.
Froome and his team have often been targeted by spectators accusing them of doping, especially in 2015, when he had urine thrown at him during one stage.
This year, Sky have come under further scrutiny with British politicians looking into the circumstances surrounding why a jiffy bag containing medication was delivered to 2012 Tour winner Bradley Wiggins at a race a year earlier.
"It does not really affect much of us on the road," Froome said of his former team-mate.
"It is different for Bradley and others who are no longer on the team, but for us it's really not a big deal, none of us have been involved in this."
The Tour de France starts in Dusseldorf, Germany on July 1 and ends in Paris on July 23.