Race leader Michael Matthews won the second stage of Paris-Nice after Nacer Bouhanni was disqualified.
France's Bouhanni crossed the line first at the end of the 213.5km stage to Commentry, the longest of the event.
But the Cofidis rider was ruled to have changed his line in the sprint finish, blocking Matthews who was subsequently handed the victory.
"I would have won if we hadn't touched," said Matthews, 25, who also won the opening Prologue.
Italy's Niccolo Bonifazio was promoted to second place, with Bouhanni demoted to third.
Australian Matthews now holds a 14-second lead over Dutchman Tom Dumoulin.
Team Sky's Geraint Thomas is in fifth place, 19 seconds off the leader, with reigning champion Richie Porte of Australia in 10th.
Wednesday's third stage runs over 165.5km from Cusset and finishes with a climb to the top of Mont Brouilly.
Stage two result:
1. Michael Matthews (Aus/Orica) 5hrs 4mins 26secs
2. Niccolo Bonifazio (Italy/Trek) Same time
3. Nacer Bouhanni (Fra/Cofidis)
4. Alexander Kristoff (Nor/Katusha) +1sec
5. Arnaud Demare (Fra/FDJ)
6. Ben Swift (GB/Team Sky)
7. Andre Greipel (Ge/Lotto)
8. Wouter Wippert (Net/Cannondale)
9. Adrien Petit (Fra/Direct Energie)
10. Jonas Van Genechten (Bel/IAM Cycling)
17. Geraint Thomas (GB/Team Sky)
Overall classification after stage two:
1. Michael Matthews (Aus/Orica) 9hrs 41mins 46secs
2. Tom Dumoulin (Net/Giant) +14secs
3. Patrick Bevin (NZ/Cannondale) +19secs
4. Jon Izagirre (Sp/Movistar)
5. Geraint Thomas (GB/Team Sky)
18. Alberto Contador (Sp/Tinkoff)
19. Simon Yates (GB/Orica) +37secs
21. Ben Swift (GB/Team Sky) +38secs