The 24-year-old midfielder has admitted that Los Blancos were made to look silly by Marcelo Bielsa's men during their clash at the Santiago Bernabeu back in January
Los Blancos defeated Marcelo Bielsa's side 4-1 at the Santiago Bernabeu in January but the final scoreline flattered the hosts, who were fortunate to have gone in at half-time level after Marcelo cancelled out Fernando Llorente's opener.
Consequently, while Madrid can clinch the title with a victory in the Basque country, Granero is not taking the three points for granted.
"They are a tough team and they embarrassed us at times at the Bernabeu, especially in the first half," the midfielder is quoted as saying by his club's official website. "As such, it will be a hard game.
"They have had a very good season and have taken a big step forward. Their coach [Bielsa] has helped them grow and they are a team of young and ambitious players."
However, Granero remains confident that Madrid, who have won their last four games in La Liga, can get the job done at San Mames and claim their first league title since 2007-08 with two rounds to spare.
"Lately we've been successful there and we will try to bring the three points back to Madrid," the 24-year-old stated.
"I've won many league titles as an amateur and now I want to celebrate one as a player. We are close, although we have not achieved anything yet."
Madrid's crunch clash with Athletic on Wednesday gets under way at 22.00CET.
Starting last month and continuing for 10 weeks, Goal.com is publishing exclusive extracts from Luca Caioli's new book, Ronaldo: The Obsession for Perfection. The sixth extract, published on Friday, looks at his display for Man Utd in the 2008 Champions League final against Chelsea in Moscow, including the Portuguese's missed penalty in the shoot-out. Don't miss it!