The Dane took advantage of a sublime two-man lead-out train to launch himself around the final corner to comfortably take the stage win ahead of Fred Wright (Bahrain Victorious) and Gianni Vermeersch (Alpecin-Deceuninck) in a reduced bunch sprint.
The Dane's Trek-Segafredo squad had been in control of the race for much of the stage, which took in two second-category climbs before a long descent and flat run-in to the finish. Having helped bring back the day's break with 50km to go, they came to the fore once again in the final to deliver Pedersen to the win.
The team had control of the 55-man peloton heading into the final kilometre, though Miles Scottson (Groupama-FDJ) threatened to upset with a late solo attack. That was no problem for Pedersen, though, who launched at 175 metres to go and never looked back.
Wright, who had picked the right wheel to follow, managed to get into the wind and looked to come alongside Pedersen in the closing metres. However, he never had enough to pull alongside fully or nudge past. Vermeersch took third but was never in the picture for the stage victory, while Ben Turner (Ineos Grenadiers) and Mike Teunissen (Jumbo-Visma) took third and fourth further back.
"It was definitely really hard to control the bunch today, but the team did so impressive," Pedersen said after the stage. "Everyone was so dedicated and working really hard. When the 3 guys went with McNulty it wasn't an easy break, so we rode really hard to close them as fast as possible.
"Everyone on the team was just so, so impressive today so I'm really thankful for the boys today. It's definitely a win for them and without them there's no chance I could have sprinted here.
"Miles Scotson attacked, and I still had Antonio Tiberi in front of me. He looks skinny but he's a powerful little guy. I was pretty sure that he could keep him in a distance where we could pass Miles in the sprint.
"It's never easy in a final like this because it's a lot of good guys in the peloton and if one of them comes with an attack on one of the roundabouts I would be the guy to close it and then it would be hard to sprint, so I was really happy with the speed the boys could keep.
"Three wins is way more than we came here for, so that's super, super nice. Tomorrow we just have to finish the day and then in Madrid we have to see how it goes. No matter what, we can be happy with these three weeks in Spain."
The stage passed with precious little action, barring the early fight for the breakaway and the final sprint, meaning that there would be no change in the general classification. The overall contenders lay low on the second-category Puerto del Piélago, preferring to save their bullets for the final mountain stage to the Puerto de Navacerrada on Saturday.
Remco Evenepoel (QuickStep-AlphaVinyl) remains in the race lead with an advantage of 2:07 over Enric Mas (Movistar), with the rest of the top GC contenders remaining in situ behind.
Pedersen's stage win hands him another 30 points to extend his already mammoth points classification lead – he now has 379 to Fred Wright's 174 in second place. In the mountain classification battle, meanwhile, Richard Carapaz (Ineos Grenadiers) picked up five points on the second of the day's ascents to take his total to 50, almost double of second-placed Mas.
How it unfolded
Sandwiched between mountain stages to the Alto del Piornal and the Puerto de Navacerrada, stage 19 of the Vuelta a España brought one final chance for the sprinters and breakaway men on a day circuiting Talavera de la Reina.
The 138.8km stage would suit the likes of green jersey wearer Mads Pedersen (Trek-Segafredo) despite featuring two second-category ascents of the Puerto del Piélago (8.9km at 5.9%). The second climb, though, would peak 43km from the finish, with a long descent giving those dropped a chance to get back on.
It was no surprise that a swathe of riders went on the attack from the start of the stage, with numerous men including Fred Wright (Bahrain Victorious), Daryl Impey (Israel-Premier Tech), and Chris Harper (Jumbo-Visma) jumping away in the early kilometres.
That move – which included 16 riders – didn't stick, however, as a three-man group managed to separate themselves soon afterwards. Ander Okamika (Burgos-BH), out in the break for the fifth time in the race, was joined in the attack by Jonathan Caicedo (EF Education-EasyPost), and Brandon McNulty (UAE Team Emirates).
Lawson Craddock (BikeExchange-Jayco), who had been in the break five times, battling for victory on stages 5 and 17, set off in pursuit of the trio soon after. The American's time in the chase was short lived, though, with the peloton catching him as Trek-Segafredo held the break's advantage at two minutes.
That wasn't it for the battle to get out front, with a large group attempting to move clear after 20km of racing, with Craddock again going and then pushing on solo as the riders hit the first ascent of the Puerto del Piélago.
The peloton hung four minutes back as Craddock made it to within a minute of the lead, though his second attempt would again fall short, eventually being caught later at 76km to go.
McNulty took the five points over the top of the day's first climb, though it would have no effect on the KOM battle, with new leader Richard Carapaz (Ineos Grenadiers) well clear in the classification.
There would be few incidents on the way down the descent, with Trek-Segafredo continuing to limit the break's advantage. Bahrain Victorious joined them at the front of the peloton as they hit the second ascent of the Piélago a minute behind the leaders.
As the race hit the final 50km, midway up the climb, McNulty was the first to be caught from the break. The American was quickly joined back in the peloton by his breakmates Caicedo and Okamika, the Burgos-BH man the last to be reabsorbed as Mikel Landa did the work at the front for teammate Fred Wright.
No further attacks came on the climb as Bahrain Victorious continued to control, though Carapaz did jump off the front at the very top to grab five more mountain points. On the way down, QuickStep-AlphaVinyl and UAE Team Emirates took over at the front to protect their GC men.
The descent, interrupted in the latter stages by three small lumps, was a quiet affair, with little appetite for attacking from the peloton and the likes of Bahrain Victorious, Trek-Segafredo, and Movistar happy to control the race.
On the flat run to the finish there was no change in the situation, the peloton speeding along back towards Talavera de la Reina ahead of what most expected to be another Pedersen sprint victory.
His Trek-Segafredo team duly took it back up on the front of the peloton as the riders upped the pace with the green jersey in their wheel heading into the closing 10km of the day. They were joined up front by several teams, including Ineos Grenadiers, Bora-Hansgrohe, and QuickStep-AlphaVinyl as the group sped into the final 5km.
Trek-Segafredo were back in charge at the sharp end of the race when it mattered most, though, their riders peeling off until all that remained were Antonio Tiberi ahead of Pedersen.
The Italian dragged back the late, late attack from Miles Scotson in time for the sprint to be launched, which Pedersen did with perfect timing. From that point on, there was no question over who would be standing on top of the podium after the stage.
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