Atletico signed Llorente from Real Madrid last year to strengthen their midfield, after selling Rodri to Manchester City, but is in the process of reinventing himself as a forward.
The great nephew of Real Madrid's six-times European Cup winning winger Paco Gento, Llorente showed his ability in front of goal with two extra-time strikes against Champions League holders Liverpool in March.
"What's happening with Marcos is similar to when Griezmann came here, and I saw him as a second striker or a centre-forward when everyone was telling me he was just a winger," Simeone said ahead of Atletico's game against Real Valladolid on Saturday.
West Ham weigh up move for £60m Calvert-Lewin - Paper Round
"When players show they have certain tools it's up to coaches to try and take advantage of them. We could see Llorente was scoring goal after goal in training and you have to make the most of opportunities like this in football."
Griezmann joined Atletico from Real Sociedad in 2014 and began as a wide player but went on to become the team's top scorer in all five seasons before moving to Barcelona last year for 120 million euros ($134.76 million).
Llorente had only struck three career goals before his brace at Anfield but has continued where he left off since the season resumed after the COVID-19-forced hiatus, scoring and getting two assists in a 5-0 drubbing of Osasuna on Wednesday.
"Marcos used to think he could be a striker and watching him train every day, with his strength and his confidence when shooting at goal opened up the option of trying it out," added Simeone.
"He's still an important option in midfield because he brings vision and quality to our play... But he's another alternative in a position where it is not easy to find a balance in order to get the team to really play." ($1 = 0.8905 euros) (Reporting by Richard Martin Editing by Christian Radnedge)
Guardiola: ‘Man City need to play like today’ despite Southampton draw
Premier League
'I didn't expect to have this lead' - Guardiola not worried by City draw,