Madrid - Former Tour de France winners Alberto Contador and Chris Froome will go head-to-head in their first outing of the 2015 season in the five-stage Ruta del Sol in Andalucia starting on Wednesday.
Spain's Contador announced on Monday that he intends to retire after two more seasons at the top.
However, he also hinted that date could be moved forward should he succeed in becoming the first man since Italian Marco Pantani in 1998 to win both the Giro d'Italia and the Tour de France in the same season.
Contador was too good for British rider Froome as he stormed to a third Tour of Spain triumph in September, but is desperate to make up for the disappointment of having to retire during the 10th stage of last year's Tour de France after suffering a broken leg in a heavy crash.
"I start my season in two days and I am desperate to get going, I have trained a lot," Contador said on Monday.
"I am a rider that likes to compete. We will see what shape I am, perhaps I will be a little slower than last year with this great Giro-Tour challenge I have planned.
"Obviously, when you plan something it is because you want to win. I don't settle and I wouldn't sign for anything other than first place in both. It doesn't mean I am going to win or that it will be easy, to win one will be really difficult, much less both of them."
Kenyan-born Froome has also stressed that the Tour de France remains his priority after he too had to retire just five stages into the defence, of the race he won in 2013, last year.
Last year's Giro champion Nairo Quintana misses out after crashing at the Colombian national championships last week and his Movistar teammate Alejandro Valverde is skipping the event despite winning in Andalusia for the past three years.
The race should therefore provide an early season pointer as to which man is in better shape with Contador and Froome expected to battle it out for the general classification victory.
A split stage on Wednesday will provide the first test with a short 118km stage followed by an 8.2km individual time trial.
However, the real intrigue will come on stages three and four with steep mountain climbs to the finish on Friday and Saturday.
List of stages
Stage 1A: February 18 - La Rabida to Hinojos, 118.3km
Stage 1B: February 18 - 8.2km individual time trial through Coria del Rio
Stage 2: February 19 - Utrera to Lucena, 191.7km
Stage 3: February 20 - Motril to Alto de Hazallanas, 157.6km
Stage 4: February 21 - Maracena to Alto de Allanadas, 199.8km
Stage 5: February 22 - Montilla to Alhaurin de la Torre, 169.8km