Kaden Groves pipped Juan Sebastian Molano in a thrilling bunch sprint finish to win Stage 4 of the 2023 Vuelta a España on Tuesday, hours after Spanish police said they foiled an attempted plot to sabotage the race.

Four men, arrested Saturday, had planned to release 400 liters (88 gallons) of "a liquid similar to motor oil" onto the road, apparently as part of a pro-Catalan independence protest.

The third Grand Tour of the season has been hit with problems in the opening stages, from bad weather to reigning champion Remco Evenepoel crashing into a spectator after the finish line Monday as he won Stage 3.

UAE Team Emirates' Colombian rider Molano launched first in Tarragona and looked set to triumph, but Australian sprinter Groves, riding for Alpecin-Deceuninck, roared past him to clinch the stage victory.

"I thought (I could win) because he had led out for 350 meters, and a finish like that is super tough," Groves told Eurosport. "I thought he would have to be on a really good day to beat me. It's been a good year, with a stage win in the Giro and already winning in the Vuelta quite early. Hopefully it's not the last."

General classification leader Evenepoel keeps the red jersey and holds a five-second lead on second place Enric Mas, with back-to-back Tour de France winner Jonas Vingegaard fourth, 31 seconds behind.

The relatively flat first section, starting from Andorra and heading back toward Catalonia's seaside, allowed a quick pace to be set, with the peloton not allowing the breakaway of Eduardo Sepulveda, David Gonzalez and Ander Okamika off the leash.

The break survived both of Stage 4's two big climbs, but they were caught by the peloton with under 20 kilometers remaining.

In the middle of the bunch, several riders crashed, including Bryan Coquard and Santiago Buitrago, four kilometers from the finish, while EF Education-EasyPost rider Marijn van den Berg fell on a tight final corner.

Stage 5 on Wednesday takes riders 186.5 kilometers from Morella to Burriana, with another sprint finish expected, plus one mountain challenge.

This is the 78th edition of the race, which ends in Madrid on Sept. 17 after 21 stages and 3,153.8 kilometers.