After a 2-0 victory in the first leg at Camp Nou, Atletico captain Koke, an academy graduate who played in their Champions League final appearances in 2014 and 2016, both reached after beating Barca in the last eight, acknowledged the importance of the week.
"Obviously, this could be a match for our history books," Koke told a press conference on Monday. "Reaching the semi-finals again after so many years would be incredible, and we're not thinking about the Cup final yet. We have to play this one as if it were a final."
Koke, 33, reflected on his 2014 goal that eliminated Barcelona.
"I've watched it several times," he said. "When matches like this come around, you draw on those memories to fire yourself up."
If Atletico's cup form this season has been strong, their LaLiga campaign has fizzled out. Three consecutive defeats - by Real Madrid, Barcelona and Sevilla - have effectively ended their title hopes, though Simeone has rotated heavily in those matches to prioritise the cups.
Barcelona lead the table with 79 points, nine clear of Real Madrid. Villarreal are third on 61, with Atletico fourth on 57, 11 ahead of fifth-placed Real Betis with seven games remaining and a Champions League berth next season all but secured.
Barcelona, trailing by two goals, travel to a stadium where Atletico have lost only three matches in all competitions this season, none by more than one goal.
"It's only natural that they're feeling hopeful. But my teammates are absolutely raring to go – they respect the opposition, but they're determined to win the match," Koke said. "Barcelona are a team that suffocate you and put you under pressure, and we need to show the character to keep possession."
Atletico are bidding for their first domestic cup crown since 2013 against Sociedad- on Saturday.