Thiem has benefitted from the injuries to Murray and Djokovic in the second half of 2017 by moving up to a career-high of fourth in the world rankings.
And while the Austrian knows they will make it tougher for him to remain in that lofty spot, he also believes they will not necessarily match Federer and Nadal, who split the major titles in 2017 after time off in the previous season.
“Every [one] of these big names when they come back, they make everybody’s life hard, of course,” Thiem said.
“But I think it’s good for the sport that they come back.
“We will see how they do.
“It’s tough to make a comeback like Roger and Rafa this year did. So we’ll see.
“But for sure it’s tougher to keep a high ranking when everybody is back.”
Thiem appeared hampered by a knee injury of his own in his last match of the season, a 6-4, 6-1 defeat to David Goffin at the ATP World Tour Finals.
However, he insisted it was just a cut which he had treated during the match, although his performance suggested it affected him more than he would like to admit.
But it seems unlikely to keep him out for any stretch of time and the 24-year-old is already looking forward to taking on a full-strength field in 2018.
“For us personally I think it doesn’t matter if [Djokovic and Murray] come back,” Thiem added.
“I think in general it just gets tougher to win big titles and to stay up high in the ranking because they are so good players.”