Last month Dumoulin announced his decision to once again make the Giro the principal target of the coming season, though he is also planning to go on to target the overall classification at the Tour, having finished runner-up in both races in 2018.
Kelderman, who finished 7th at the Giro in 2014, has been Team Sunweb's secondary Grand Tour leader for the past couple of seasons. After supporting Dumoulin to Giro victory in 2017, he finished fourth at that year's Vuelta a España, and while injury prevented him from supporting Dumoulin at the Tour in 2018, he went back to Spain to record another top-10 finish.
This year, the 27-year-old will not, in theory, have a chance to target a three-week race for himself, his team choosing instead to deploy him as Dumoulin's right-hand man. The team's Grand Tour plans were announced at a team presentation in Berlin on Thursday.
"I had a different program in my head, but when Tom decided to ride the Giro I knew it would be this scenario," Kelderman said, according to De Telegraaf.
"I see it as an opportunity. At first I was not happy with it. But I also realise that there are enough races where I can go for my own success - in Paris-Nice, for example, or the Volta a Catalunya. But in the Grand Tours I often ride as the second or third man. It might also suit me a bit. I often work best in the shadows."
Sam Oomen, the 23-year-old Dutchman who so impressed with his work for Dumoulin at last year's Giro - where he even bagged a top 10 finish himself - will not be by Dumoulin's side in Italy. Instead, he will be there at the Tour de France, making his debut in the Grande Boucle.
Oomen made his Grand Tour debut at the 2017 Vuelta and rode the Giro last year, but will not ride two three-week races in the same season this year, with the Vuelta not currently on his programme.
Instead, there are set to be plenty of riders with a free role in Spain. With Team Sunweb not targeting the general classification, the nominal leader will be sprinter Max Walscheid, who won the Munsterland Giro this year.