Michael Laudrup's side thrashed their below-par opponents at the Liberty Stadium last Thursday, and will be confident of sealing their qualification amid a heavy police presence
A double from Wayne Routledge, efforts from Michu and Alejandro Pozuelo as well as a Peterson Pecanha own-goal made Gheorghe Grozav's late away goal barely relevant in the sides' play-off first-leg clash at the Liberty Stadium last week.
Michael Laudrup's only injury concern is Nathan Dyer, who has been struggling with a hamstring strain, but he could well rest key players with the scoreline set so heavily in his side's favour.
Pozuelo is yet to make a start for Swansea since moving from Betis in the close-season and is hoping Laudrup will see fit to include him in the XI, having also scored from the bench against Malmo in the third round of qualifying.
He told the club's official website: "I feel that I am improving each day in training and just by being part of the squad.
"For this game we are leading 5-1, but we still have to be professional and progress.
"This is an important game for us, because hopefully I will get another opportunity to show the manager that I can play and be important for the team for the rest of the season.
"To reach the group stages would be really good for us – but first we must come through our second leg on Thursday."
Swansea have started their Premier League campaign with two defeats against Manchester United and Tottenham, going down 1-0 at White Hart Lane on Sunday courtesy of Roberto Soldado's penalty.
Petrolul Ploiesti currently sit third in Romania's top flight with three wins and three draws from their opening six fixtures.
The club have called for fans to be on their best behaviour after a series of unsavoury incidents during a home draw with Ceahlaul Piatra on August 17.
Thursday's tie represents their first fixture at their Ilie Oana stadium since and a heavy police presence is expected.
Manager Cosmin Contra - a former AC Milan, Atletico Madrid and Romania right-back - played under Swansea manager Laudrup at Getafe.