Ireland's Daniel Martin extended his overall lead of the Volta a Catalunya to 14 seconds following the fifth stage.
Martin caught out his major rivals, including Tour de France champion Sir Bradley Wiggins, in a sprint finish that splintered the riders.
Canada's Francois Parisien claimed the stage win but Martin's ninth placing ensured he increased the gap over closest challenger Joaquim Rodriguez by four seconds.
Wiggins and Nairo Quintana were nine seconds off the pace, after they had opted to stay out of trouble at the end only to see Martin take his chances to increase his lead.
Fourth-placed Wiggins will therefore head into Saurday's penultimate stage 44secs behind his Irish rival, with Quintana two seconds better off.
Parisien won the 156-kilometre stage, from Rialp to Lleida, after he sprinted past Stephane Poulhies in the final 75m.
The race finishes in Barcelona on Sunday.