Madrid - Chris Froome returns to competition on Wednesday in the Ruta del Sol but he will be riding under a cloud after the revelation in December of an abnormal doping result.
Froome has the right to ride because salbutamol, the substance that showed up in the test, is an anti-asthma drug which can be taken legally and so does not lead to an automatic ban.
Cycling's international governing body (UCI) still has to make a ruling on the case and has asked Froome to explain why twice the allowed limit showed up in his sample. But the reaction of other riders suggests that the presence of the four-time Tour de France winner in the five-day race through Andalusia may provoke some resentment in the peloton.
UCI chief David Lappartient said last month that Froome should be suspended over the adverse test and some of the rider's main rivals have hit out at cycling authorities for failing to ban him.
Despite the criticism, Froome, who has not raced since September, is preparing to start his 2018 season in the same country where he returned the controversial test on September 7 as he headed for victory in the Spanish Vuelta.
"About to head to Ruta del Sol. I want to thank everyone for their support & patience over this difficult period. I am doing my utmost to ensure that things are resolved as speedily as possible. Can't wait to get this season started!!" Froome wrote on Twitter on Tuesday.
Froome, who won the race on his last appearance in 2015, should be one of the favourites over a course which contains a mountain-top finish on Thursday and ends in a time trial that could have been designed for the 32-year old Briton.
If he succeeds in clearing his name, this race could prove an important stepping stone for success on the road later in the season. He needs miles in his legs to prepare for his bigger objectives: the Giro d'Italia, which starts on May 4, and the Tour de France, starting July 7, where he would be chasing a record-equalling fifth victory.
On the other hand, if he is later banned then he would be retrospectively disqualified, meaning he could be distorting the competitive balance of the Ruta by riding.
Whatever the future verdict, Froome can expect to be the centre of intense attention, from the media, the fans and cycling professionals in his first race since the news of his test result.
He did not appear at the pre-race press conference on Tuesday but could find himself facing the microphones on Wednesday, before or after the opening stage from Mijas, on the Mediterranean coast and Granada on the slopes of the Sierra Nevada.
"Obviously I understand that this situation has created a lot of uncertainty. I completely get why there has been so much interest and speculation," Froome said in a statement on Team Sky's website last week.
Sky have not yet submitted the scientific evidence which might justify Froome's abnormal sample. The team said in December they were providing information to the UCI and confirmed in a statement last Monday that the process was ongoing.
Team principal Dave Brailsford said: "We all recognise that these are difficult circumstances but it's important for all sides that this process is conducted fairly before a final conclusion is reached."