Eighth in the Vuelta a Andalucia's final race against the clock last year was enough to clinch Wellens the overall title and this time around his second stage win in three days could prove equally critical for his chances of a second straight title in the Spanish stage race.
The provisional best time changed no fewer than four times as the last half dozen riders crossed the line, and Wellens winning margin on the highly technical finale was a narrow two seconds over Astana's Jakob Fuglsang, the rider off just ahead of him.
But a win is a win, no matter the margin, and although his advantage overall now stands at a scant seven seconds over Fuglsang and 14 over the Danish rider's Astana teammate Ion Izagirre, after delivering so impressively on a technical and challenging time trial course Wellens could afford to feel very upbeat indeed ahead of Saturday's crunch mountain stage.
"It was a very hard time trial, for everybody it was," Wellens told reporters afterwards.
"I couldn't find the Watts [power output] I wanted at the start and I couldn't go as fast as I wanted to. It was only in the second half that things really came right."
Asked why his time trialling had improved so much nonetheless, Wellens said, " [Performance manager] Kevin De Weert came into the team [during the off-season] with a lot of different goals and knowledge and that makes a big difference. Everything is very carefully planned."
Focussing more specifically on Andalucia, Wellens said, "Kevin came here with the car and filmed everything about the route so, from day one I've been looking at videos of the parcours, I knew it suited me very well."
"But also" - again, thanks to De Weert's films of the route - "I knew that today had a technical downhill and I could take the corners the way I wanted, I could take a lot of risks and I think that gave me the chance to win today."
Wellens argued that rather than Saturday's mountain stage, Friday's time trial was the most critical for the battle for the overall, and he showed he was confident about claiming a second outright win in Spain's toughest early season race in two years. Rather than having to go on the attack in the mountains, he pointed out, he could play a conservative game.
"Tomorrow [Saturday] will hurt but I have to follow wheels. It's only 120 kilometres long, and there are no bonus seconds on the stages, which is good for me.
"But I am sure Astana will attack on Monachil [the first climb, also known as El Purche - Ed.] to make it hard. We will see how my legs respond."
The 27-year-old agreed that his Polish teammate Tomasz Marczynski, who lives near Sierra Nevada, would be crucial as a guide on the two tough climbs in southern Spain's biggest mountain range.
"Tomasz knows the climbs very well, he lives just 10 kilometres away. But I came to Sierra Nevada myself to a training camp a few years back so I've been over them too. I know that they are very steep and they'll bring a lot of fireworks from the Astana guys."
"For me, it's much better that Saturday's finish is not at the top of the climb. The downhills are fast and broad, and it'll be difficult for a single guy to stay away, and that's to my advantage."
Astana's riders promised they would not give Wellens an armchair ride to victory on Sunday in Alhaurin de la Torre, but Izagirre insisted after the time trial that Wellens "right now, is the strongest rider in the race, and we can only congratulate him for that."
"Our team is strong, though, we placed three riders in the top ten today" - Fuglsang in second, Izagirre in third and Vuelta a Murcia stage winner Pello Bilbao in seventh - "so we'll be on the lookout to see what we can do to beat him."