In addition to the Europa League, Tottenham are also in the FA Cup and have a 1-0 advantage over Liverpool in the Carabao Cup semi-final.
Victory over Hoffenheim means that Spurs' win at home to Elfsborg next week will likely take them into the knockout stage.
This match comes two big days before Tottenham as they travel to Liverpool in the EFL Cup on February 6 before going to Aston Villa in the FA Cup fourth round three days later.
Around them they have important league games against Leicester, Brentford and Manchester United as they look to avoid falling from their current 15th place in the Premier League.
“It's a big couple of weeks for the club,” Hargreaves added.
“It defines their season, with the FA Cup and the second leg of the League Cup.”
Former Tottenham striker Peter Crouch said: “They are one game away from the final.
“They're on the rise there. If they get to the final it's a good season.”
Tottenham are now among the favorites to win the Europa League.
With a top-four finish likely, success in Europe's second-tier competition is the best way to secure Champions League football next season.
Crouch added: “The Europa League should be a priority now.”
“I look at the teams and they can beat any of them.”
