While victory offers not much more than the prospect of a more favourable Nations League quarter-final in March, it would be a landmark moment for England if they could end Spain's run of 43 matches without defeat.
"It (Spain) is a team that has forgotten how to lose, so of course it requires a top performance first of all, and if we can deliver this performance, it will give us a big boost," said England manager Tuchel, whose side beat Croatia 2-1 at Wembley on Thursday.
"I think we're there, and I think we're ready to win on Sunday," the German added.
"I know what it takes, and no one can ever guarantee it, but I think it's the moment to check how far we are and to push our limit and proof of concept."
England lost the reverse fixture 3-2 at Wembley in September, but it might have been a different story had Harry Kane scored a penalty to put Tuchel's team 3-1 up.
"It's important that we play with the same mindset that we played at home, and attack them and try to make it a physical game, and try to impose our strength," he said.
England players have previously faced racist abuse in Spain, with Ashley Cole and Shaun Wright-Phillips targeted during a friendly in Madrid in 2004.
Spain, meanwhile, must play their next home friendly with a reduced capacity as a punishment for supporters singing a discriminatory chant about Muslims during a fixture against Egypt in March.
"We will never accept racism," said Tuchel. "We will never be racist towards anyone."
He added: "I expect, of course, full support from the Spanish crowd for the Spanish team. But we will not expect anything. And I think the referee and the officials know about that... There is a protocol in place and it's important that the players know about the protocol.
"We will give our answers if stuff like this happens. Best answers are on the pitch."
