Atletico are well placed to finish fourth behind champions Barcelona, Real Madrid and Sevilla, who have secured the three automatic qualification places.
They have won five in a row and only need a point from the visit of mid-table Almeria on Saturday to make the qualifying stages of Europe's elite competition.
The man responsible for getting them there is Uruguay striker Forlan, who has netted 11 times in the last seven games to take his season tally to 31.
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"He's an ambitious lad. As well as working for the team he makes the difference," Atletico coach Abel Resino said after Forlan scored a hat-trick in the 4-1 win at Athletic Bilbao last weekend.
"It seemed as though he wasn't in the game and suddenly he scores two vital goals and then a penalty."
Forlan, who has just turned 30, won the Golden Shoe jointly with Thierry Henry in 2004-05 after scoring 25 goals for Villarreal.
His former club are the only ones capable of pipping Atletico for fourth.
Manuel Pellegrini's side are two points back in fifth, with an inferior head-to-head record, so need to win at Real Mallorca on Saturday and hope Atletico lose.
FIVE TEAMS
The final weekend of the season starts with five teams separated by two points and scrapping to avoid the one remaining relegation place.
The four matches that will decide who joins Recreativo Huelva and Numancia in the second division next year all kick off at 4pm on Sunday.
Osasuna occupy 18th place with 40 points, behind Sporting Gijon on the head-to-head rule. Real Betis are behind Getafe on 41 points for the same reason.
Real Valladolid are closest to safety in 14th with 42 points but are on the worst run of form having gone 10 matches without a win. They visit direct rivals Betis.
Getafe travel north to face mid-table Racing Santander, Sporting are at home to Recreativo and Osasuna host a Real Madrid side with nothing to play for and four consecutive defeats behind them.
Victory for any of the teams would guarantee their survival, which promises to provide a nail-biting finale to the season.
