In a fitting way for the club to pay tribute to club legend Luis Aragones, who passed away a day earlier, David Villa opened the scoring late in the first half and then dedicated his goal to the late coach, with whom he won Euro 2008 with Spain.
Diego Costa settled Atletico's nerves by scoring the second goal with 18 minutes remaining, and then Joao Miranda and substitute Diego Ribas each scored later on to round off an emotional night.
Ten-man Real Madrid missed the chance to move into second as they were held to a 1-1 draw away to Athletic Bilbao.
Jese Rodriguez fired Real ahead after 64 minutes and Ibai Gomez struck back 10 minutes later for the home side, moments before La Liga top scorer Cristiano Ronaldo saw red for the visitors for violent misconduct.
The draw leaves Real in third place, level on points with second-placed Barcelona but with a four-goal difference, while Bilbao remain fourth, 11 points further back.
Ruben Castro fired Real Betis to their first win since September with a late double strike.
The 2-0 success against Espanyol meant new head coach Gabriel Calderon's first home match in charge was one to remember, and allowed Betis to see a glimmer of light through the relegation trap door.
Betis have looked doomed to the drop, having become increasingly marooned at the foot of the table while their winless stretch has continued.
They are still floundering eight points adrift of Almeria in 17th place, but Argentinian Calderon will see it as a start.
After four barren months, Betis needed something to cling to and star forward Ruben gave them it, netting in the 71st and 89th minutes.
Elche moved four points clear of danger after earning a narrow but deserved 1-0 win at home to fellow strugglers Almeria.
A fortuitous goal from Cristian Herrera after 59 minutes was all it took for Fran Escriba's side to take all three points, although they had to endure a nervy few minutes of injury time after Damian Suarez was sent off in the 90th minute for picking up two yellow cards.
The result means Almeria replace Elche as the team occupying the final spot above the drop zone, while the Alicante side move up to 15th in the table.