Alonso said there was excitement and enthusiasm in a team whose preparations were exceptional going into their three matches in Group H, where they also meet Ghana and Portugal.
"Uruguay players are the best in the world, they defend us through thick and thin," Alonso told a news conference on Wednesday.
"That's the most important tool we have is the feeling the Uruguayan players have, how they identify themselves, the sense of belonging they have."
World Cup winners in 1930 and 1950, Uruguay, a nation of only 3.5 million people, have a knack of causing upsets and making extended runs during their 14 appearances in the tournament, making them wildcards each time, and a team big names hope to avoid.
Alonso said he was not talking out of arrogance or referring to the individual ability of his players, but about their determination to deliver for their country.
"When I say Uruguayan players are the best in the world it's because they're my players," he said, drawing parallels with the love of his children.
"Uruguayan players respect the team, that's why they're the best."
The squad was injury free, he said, except for Barcelona defender Ronald Araujo, who underwent thigh surgery in September but was making good progress.
"He's playing well every day. His body will tell us when he's fit," he added.
Alonso joined Uruguay in December last year, replacing Oscar Tabarez after 15 years in charge of the national side.
He has picked a squad with a huge age gap, which includes six players 35 years or older - some with four World Cups under their belt - alongside 13 first-timers, among them Liverpool striker Darwin Nunez.
Longtime captain Diego Godin is 36 and in Qatar will add to his more than 150 appearances for Uruguay. He played down questions alluding to the impediments of his age.
"The Godin of 20 years ago was different but I give my utmost, my everything on the pitch," he said.
"We're very eager, very excited and have that enthusiasm you usually feel before first match is a feeling we all share. Tomorrow is moment of truth and we will speak on the pitch."
