Bernal (Ineos Grenadiers) has also put doubts on whether he will be on the plane to Tokyo for the Olympic Games later on in the summer.
The Colombian climber has put on a truly incredible show at the Giro so far, leading the race by 2-24 over his nearest rival, Damiano Caruso (Bahrain Victorious) thanks to his attacks in the mountains.
Speaking in his rest day press conference, Bernal said: "I think I won’t go to the Tour, I think guys who are now in the Tour team can do really well.
"I prefer to just focus on the second part of the season, maybe ride La Vuelta [a España]. I’m not sure about the Olympics because I still have problems in my back.
"I’m not going to lie, it still hurts me sometimes, more than anything up to half way through than at the end of the stages,
"It worries me because this could be affecting the lower back and all that area. We are doing physiotherapy every day and I think it’ll hold up for the rest of the race, I don’t think the pain will suddenly go off the scale. So I’m confident all will be well until then."
Bernal's back problems emerged during the 2020 season, believed to be caused by a discrepancy in the length of his legs, and after he fell out of contention on stage 15 of the Tour to Grand Colombier, he then pulled out of the race after stage 16 to begin his rehabilitation.
Ineos Grenadiers and Bernal have worked on a strict plan for managing his back pain with the help of team coach Xabi Artetxe, who made the decision to not let Bernal race after Tirreno-Adriatico and instead return to Colombia to train.
The 2019 Tour de France winner also said that if he does not feel that he is on top form he won't go to the Olympics.
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