Riding as an all-round rider who rode well in hilly terrain, Sørensen was a valued support for the team leader without many wins of his own.

In his first year with the team he participated in the 2001 Tour de France where he got a taste of success with a fourth place on stage 16.

After then, Sørensen was a consistent part of the Tour setup for Team CSC, riding the biggest race in the cycling calendar every year from 2001 to 2005, his highlights including the overall GC rank of 20th in 2002.

In September Nicki Sørensen clinched stage 18 of the Vuelta a España after defeating Pascual Rodriguez in the sprint.

[9] In June 2015 prior to Anti Doping Denmark report he admitted to drug use in early part of his career.