The break had established a maximum lead of seven minutes as the mercury pushed through to the high-30s in scorching Catalonia. Contador remained over three minutes behind.
Frenchman Johan Le Bon (FDJ) and Australian Nick Schultz (Caja-Rural) were soon the first of the initial escapees to be swallowed up while rookie rider Juan Osorio (Manzana Postobon) gamely resisted for another 20km before succumbing to the inevitable.
Two riders, Stephane Rossetto and Diego Rubio, led a breakaway that was neutralized by the peloton with less than 10 kilometers (6.2 miles) to go. Aqua-Blue Sport rider Mark Christian was not so lucky, although he lost just skin and perhaps pride after a touch of wheels.
That ensured he retained a two-second lead in the general classification, with a 10 second advantage on his closest expected title challenger, Vincenzo Nibali, and more than 30 seconds on fellow rivals Fabio Aru, Adam Yates, Simon Yates and Romain Bardet.
The approach was dotted by some memorable crashed, one being Wilco Kelderman (Sunweb), although he was brought back to the bunch.More news: Weld County's unemployment rate sinks again
No such luck for Moreno and Pozzovivo, whose crash came just outside the 3km cut-off point.
The race ends in Madrid on September 10. It was second in the opening team time trial, Yves Lampaert and Trentin pulled off a one-two finish in the second stage, and David de la Cruz was second on the third stage.
"I was really looking for the victory because I have been going good this season", Trentin said.
In the background, Gianni Moscon paved the way for an attack from Froome, and Trek's Alberto Contador managed to stay with the Tour de France victor. Two days ago we did a ideal, smart job with Yves Lampaert, and [he] took the win and the jersey. Today we decided it was my time. "Everybody pulled together. It was really handsome coming into the finish".
"But I am really proud to do this with the Quick-Step team because next year I am going to change (team)".