The 22 teams that competed in the race were:[7] Following the introduction of a race-opening team time trial by organisers in 2011, the 2012 event began in the same fashion with a short test between the towns of San Vincenzo and Donoratico; both of which are synonymous within Italian cycling as the start and finish towns of the early-season Gran Premio della Costa Etruschi race.

[17] Caccia and Pirazzi quickly stepped up the pace to pull clear of the peloton, fronted by the GreenEDGE team of race leader Matthew Goss.

Pirazzi again crossed the line first ahead of Caccia, and thus guaranteed himself the first green jersey of the race for mountains classification leader.

Their advantage stayed largely between four-and-a-half and five minutes before entering the finishing circuit, 33.4 km (20.8 mi) in length, at Indicatore for the first of two laps.

[18] With Team Sky again controlling the pace of the main pack, Yaroslav Popovych (RadioShack–Nissan) attacked inside the final 10 km (6.2 mi), causing two other riders – Enrico Gasparotto of Astana and Fabio Taborre of Acqua & Sapone – to follow suit, but all three were swallowed up shortly after.

Gasparotto's team-mate Paolo Tiralongo then launched an attack with BMC Racing Team's Greg Van Avermaet at 3 km (1.9 mi) to go, but to no avail as they were both caught outside Indicatore.

A large crash with 1.5 km (0.9 mi) to go reduced the number of contenders for the sprint,[20] where Garmin–Barracuda tried to lead it out for Tyler Farrar, the stage-winner in Indicatore in 2011.

[24] The main field decided not to follow him closely to begin with, as he was not a factor in the overall classification; over nine minutes behind overnight leader Matthew Goss of the GreenEDGE team.

[25] Savini's brave salvo off the front of the pack ended with around 30 km (18.6 mi), as BMC Racing Team led the chase of him during the stage.

[27] André Greipel was close behind in second for Lotto–Belisol, ahead of Liquigas–Cannondale's Peter Sagan, Farrar, Manuel Belletti (Ag2r–La Mondiale) and Goss, who maintained his race lead.

[32] The main field decided not to follow them closely to begin with, with the lead increasing dramatically in the early stages, reaching an ultimate maximum gap of around twelve minutes.

Johnny Hoogerland launched a late attack for Vacansoleil–DCM,[32] but was usurped by Acqua & Sapone's Danilo Di Luca and Liquigas–Cannondale rider Peter Sagan.

[36] Goddaert was dropped on the Piano Roseto, as his two rivals looked to step up their pace in advance of the Liquigas–Cannondale-led peloton, who had been cutting into their lead quite effectively; reducing their gap out front from around 10' 30" at the start of the climb to a much smaller margin of 3' 30" by its conclusion.

With around 4 km (2.5 mi) to ride in the stage,[40] Vincenzo Nibali looked to avenge a disappointing showing in Chieti, by going on the offensive, and was not directly followed by any other rider from the main field.

A group of six riders got clear after around 3 km (1.9 mi), including world champion Mark Cavendish (Team Sky), but their move was quickly negated as the sextet could only muster an advantage of twenty seconds over the field.

Danilo Di Luca (Acqua & Sapone) and Michele Scarponi launched punchy attacks not long after,[47] as did Christophe Riblon (Ag2r–La Mondiale) and Domenico Pozzovivo (Colnago–CSF Bardiani), but Liquigas–Cannondale shut down all the moves via their points classification leader Peter Sagan,[48] who had remained with the lead group.

Sagan's closing of the group set up a final attack from Team Katusha's Joaquim Rodríguez with 1 km (0.6 mi) remaining, and held on to win his third career Tirreno–Adriatico stage.

San Benedetto del Tronto in the Marche region played host to a perfectly flat out-and-back ride right along the Adriatic coast; it was held on the same course as the 2011 edition, where Fabian Cancellara claimed victory for the Leopard Trek team, in a time of 10' 33".

[51][52] Cancellara was the pre-stage favourite,[53] but much of the focus was upon the impending three-rider battle for the overall honours between RadioShack–Nissan's Chris Horner, Astana's Roman Kreuziger and Liquigas–Cannondale's Vincenzo Nibali; the three riders were split by just six seconds prior to the stage.

Thus, Alex Rasmussen of Garmin–Barracuda, who, in 148th place,[47] trailed overall leader Horner by one hour, sixteen minutes and thirteen seconds, was the first rider to set off on the final stage.