All but one of the 18 UCI WorldTeams, and three UCI ProTeams, make up the 20 teams that are participating in the race.[3][4]Cofidis, the only UCI WorldTeam to not be participating in the race, declined their invitation, citing a full schedule.[5]Alpecin–Fenix and Arkéa–Samsic received automatic invitations as the best performing UCI ProTeams in the 2021 season,[6][7] but only the former accepted their invitation. The other two UCI ProTeams, Bardiani–CSF–Faizanè and Gazprom–RusVelo, were selected by RCS Sport, the race organisers.[8]
With many teams experiencing positive COVID-19 test results and having to withdraw riders and staff from competition,[9] only 10 teams were able to enter a full squad of seven riders, with a further seven teams entering six riders each. Intermarché–Wanty–Gobert Matériaux and Trek–Segafredo were only able to enter five riders each, while Lotto–Soudal was the only team to enter a squad of four riders. Gazprom–RusVelo also had one late non-starter, reducing their squad to six riders. In total, 125 riders started the race, of which 122 finished.[10][11]
On stage 2, Sam Bennett, who was third in the points classification, wore the green jersey, because first-placed Jasper Philipsen wore the red jersey as the leader of the general classification and second-placed Dmitry Strakhov wore the black jersey as the leader of the sprints classification. For the same reason, Mark Cavendish wore the green jersey on stage 3.
On stages 2 and 3, Xandres Vervloesem, who was second in the young rider classification, wore the white jersey, because first-placed Jasper Philipsen wore the red jersey as the leader of the general classification.
On stage 4, Tadej Pogačar, who was second in the young rider classification, wore the white jersey, because first-placed Stefan Bissegger wore the red jersey as the leader of the general classification.
On stages 5–7, João Almeida, who was second in the young rider classification, wore the white jersey, because first-placed Tadej Pogačar wore the red jersey as the leader of the general classification.