Froome and Thomas's decision to ride the Tour of Britain instead of the Vuelta is set to end Team Sky's iron grip on the Grand Tours, with the British outfit having won the last four.
Movistar are best placed to take advantage in the race, which begins on Saturday with an 8km prologue in Malaga and ends in Madrid on Sept. 16.
Motivated to improve on a disappointing 10th-placed finish in the Tour de France, 2016 Vuelta winner Nairo Quintana, along with 38-year-old Spaniard Alejandro Valverde, will lead Movistar's push for a first Grand Tour title in two years.
Their bid, however, has been weakened by injury to team mate Mikel Landa.
Italian Fabio Aru, the 2015 Vuelta champion, is out to make amends for his performance in the Giro, when he withdrew on stage 19 after suffering from exhaustion and then skipped the Tour in order to recover.
"I've always done well in the Vuelta and that's why I'm approaching it with a lot of enthusiasm and am so keen to do well," Aru told Spanish newspaper Marca.
"What happened at the Giro was not easy but now I'm much better prepared. The Vuelta is different because it isn't controlled as much as other races by the teams. It will be decided day by day, and little by little some of the favourites will start to lose their way."
SBS will broadcast all stages of the 2018 Vuelta a España.
Briton Simon Yates, who can count on the support of twin brother Adam in the Mitchelton-Scott team, is also looking for redemption after wearing the pink jersey for 13 days in Italy before running out of steam in the final week and finishing way back in 21st.
Like Aru, he should benefit from extra rest after sitting out the Tour.
Vincenzo Nibali's Tour was ended by a vertebra fracture but he has recovered in time to compete in the race where he finished runner-up last year.
The Italian, however, has stated he is not targeting a podium finish but is instead eyeing the race as practice for the UCI Road World Championships, which begin in Innsbruck a week after the Vuelta ends.
Australian Richie Porte - who missed the team presentation due to a gastro illness - will also be out to rebuild his season after his Tour was wrecked by a clavicle fracture on stage nine.
Sky's weakened challenge will be headed by recent Tour of Poland champion Michal Kwiatkowski and David de la Cruz, with the latter looking to become the first Spaniard to win the Vuelta since Alberto Contador in 2014.
The Vuelta, which this year features two time trials and nine punishing summit finishes, is considered by many as the hardest of the three Grand Tours due to its placement in the calendar and the unforgiving conditions at the height of the Spanish summer.
"I hope the Vuelta lives up to its reputation for suspense and unpredictability and with this lineup I'm sure it will," said race director Javier Guillen.
"The lineup and route guarantees excitement until the end."