Nadal – the reigning US Open champion – booked his place in the semifinals of the US Open with a gripping five-set win over Thiem on Wednesday morning UK time.
The number one in the world overtook the bagel he had in the first set on the receiving end to fetch the loot and bring himself closer to the fame of Flushing Meadows.
In the meantime, Cilic crashed out of the tournament after breaking the gap with Japanese Kei Nishikori.
And when he was asked about his thoughts about Nadal's meeting with Thiem, Cilic admitted that he had not voted for so long.
He said, "Maybe one sentence, just in the middle of the game, I went to sleep (laughing).
"But, yes, it was a great game.
"Definitely unlucky for Dominic, he plays good tennis and he also moved out in Cincy or Toronto, I'm not sure, but he was sick.
"But he hits very well, hits it well, and, you know, just pity him for failing to do it."
When asked who is the favorite between Nadal and Del Potro, Cilic Nadal has given the advantage.
He added: "Just look at their matchups, earlier this year as well, French Open and Wimbledon, I did not see Wimbledon, but French Open I have a little, and again here last year, I think in the rallies Rafa was a little better and he was able to expose Juan Martin at the rallies.
"I feel that Juan Martin beats his backhand a little bigger at this tournament.
"That can help him, you know, in the other case, Rafa had a heavier draw to go through the semi-finals, but, you know, he has two days left to recover, so he'll be fresh.
"I do not know, I would give Rafa a slight advantage, but I think it will be a great game."