This is the Belgian's final campaign, and after leading Fernando Gaviria to victory on the opening stage of the Vuelta a San Juan, he continued the perfect start with a win of his own on day two, beating Elia Viviani with a powerful sprint that will do wonders for his confidence.
Since turning professional back in 2002, Boonen has gone on to rack up well over 100 victories – among them nine Monuments, six Tour de France stages, and a rainbow jersey. His final season is a truncated one as he prepares to take his final bow at Paris-Roubaix in April – "the race where I was born as a rider" – and in San Juan he swatted away any pressure that might have crept in had the clock started to count down without reward.
"It's important for me to win so early in the season," he said after jubilant celebrations on the finish line.
"Yesterday was already very successful for us. We started out with plan to sprint for Gaviria yesterday and for me today, so I'm happy that the chance I had, I was able to take it straight away."
Boonen spoke of the difference between the manner in which he has started this season compared to the previous one. Set back by the skull fracture he sustained at the 2015 Abu Dhabi Tour, he struggled early on last year and was racing against time to find full fitness for the spring classics, only managing it at the last minute with an agonising second place at Paris-Roubaix.
This year, with a season totalling just 11 weeks, the need to be strong early on is more pressing than ever, and his performances on the first two days of racing in Argentina suggest he his right where he needs to be.
"This gives me confirmation," said the 36-year-old, who speculated that – according to feel rather than hard data – he might have just produced his highest peak power output in the best part of a decade.
"This shows I was right about my condition, and that everything is going in the right direction."
Indeed, he may be buoyed to recall that the last time he won in January in Argentina, in 2012, he went on to win E3-Harelbeke, Gent-Wevelgem, The Tour of Flanders, and Paris-Roubaix.
Ahead of the race, Boonen insisted this final road to Roubaix would not be beset by sentiment – that he would prepare as he always has done and leave the emotion for when it's all done – but he did allow a little to creep as he basked in his victory.
"It feels strange," he said. "I'm not thinking about it all the time, for sure, but there are some special days, like my last Worlds, the last training camp, the first race of the last season… Everywhere where you go you get reminders. This is the first victory of the final season, so it's always like that now for the next two or three months."