Inter return to Europe in Zanetti's send-off
Inter Milan's defender Javier Zanetti is celebrated by teammates after their Italian Serie A football match against Lazio, on May 10, 2014, in San Siro Stadium in Milan - by Olivier Morin
Zanetti, who has spent 19 seasons with Inter, was playing in his final official game before taking up a director's post with the Serie A giants.
Despite Zanetti's San Siro farewell drawing a near capacity crowd, Inter coach Walter Mazzarri left the 40-year-old Argentinian on the bench until he replaced Jonathan in the 52nd minute.
Zanetti, speaking to Sky Sport, admitted it had been an emotional night.
"I'm crying inside with the thought of leaving these wonderful fans behind after so may years of wearing the shirt and playing as captain," said Zanetti.
"I've had an incredible career. The atmosphere here tonight was something special and will stay with me forever."
Zanetti's finale was also marked by a solitary fan running onto the pitch in the 90th minute to salute the man who has come to be simply known as 'Il Capitano'.
But there was drama before then as Lazio, one of several teams fighting for the Europa league, stunned the stadium into silence when Bruno Pereirinha's cross was knocked down by Lorik Cana for unmarked Giuseppe Biava to bundle past Samir Handanovic in the Inter net.
Any thoughts Zanetti's night would be spoiled were dispelled by the half-time interval, however.
Inter were back on level terms five minutes later thanks to Rodrigo Palacio, took the lead through Mauro Icardi on 34 minutes and then put the match virtually beyond all reach when Palacio completed his brace three minutes later.
- South American rout -
Brazilian international midfielder Hernanes, who joined the club from Lazio in January, completed the all-south American rout on 79 minutes.
Inter now have a six-point lead on both Parma and Milan and, even if they finish on the same points as both or either club, have a better differential than both using the league's qualifying criteria for the Europa League.
This season, the sixth-placed finisher in Serie A will also qualify for Europa via the Italian Cup, won by Napoli over Fiorentina last week.
Although his side still have a mathematical chance of qualifying for Europe, Lazio are in 10th, two points behind Torino who still have two games to play.
Coach Edy Reja said: "I've all but given up hope of a place in Europe."
He added: "Inter wanted to win at all costs tonight. We put up a good fight but we just should not have conceded all these goals."
Earlier, Verona's Europa hopes suffered a huge dent when Ghanaian substitute Emmanuel Badu hit an injury-time equaliser for Udinese in a 2-2 draw.
Verona had provisionally sneaked into the Europa zone after goals by Luca Toni, from the spot, and Emil Hallfredsson had given them a 2-1 lead by the 54th minute.
Veteran striker Antonio Di Natale reduced the arrears for the northeners on 56 minutes amid what was a pulsating and balanced game at the Bentegodi stadium.
But barely five minutes after replacing defensive midfielder Allan in the 87th minute, Badu brought Andrea Mandolini's men back down to earth by firing a daisycutter past Verona 'keeper Rafael in the first minute of injury time.
Instead of moving up to sixth, Verona remain ninth on 54 points, the same as Milan, who are eighth, and seventh-placed Parma, ahead of their respective matches away to Atalanta and Torino.
Juventus secured their third consecutive scudetto last weekend and are away to Roma, second and 11 points adrift, on Sunday.
A win would see Antonio Conte's visitors amass 99 points and thus beat Inter's Serie A record of 97 for their title-winning 2007 season, with one game in the season remaining.
Roma are assured of the second automatic Champions League qualifying spot while Napoli, away to Sampdoria on Sunday, will play in next season's competition if they successfully negotiate the qualifying stages.
Fiorentina, in fourth, have secured the first Europa League spot but are away to a Livorno side on Sunday fighting for its top-flight survival.