With just seven days until League One kicks off, Jackett opted for a virtually full-strength side, playing in the newly favoured 4-3-3 system.
Line Up: Gueret, Monk, Ricketts, Austin, Iriekpen, Martinez, Britton, O'Leary, Forbes, Goodfellow, Trundle.
Subs: Murphy, Anderson, Gurney, Tate, Tudur-Jones, McLeod, Robinson, Connor.
Garry Monk returned to the first-team in place of Alan Tate, whilst Marc Goodfellow replaced the injured Adebayo Akinfenwa in attack, with Lee Trundle playing in the central striking role.
Swansea began with great promise and almost took the lead when Adrian Forbes uncharacteristically headed wide from a great position within the Blackburn box. Just moments later, O'Leary almost opened the scoring with a header from a similar position, after the Blackburn defence failed to get their marking right from a Marc Goodfellow corner.
However, Blackburn slowly began to come into the game and Brett Emerton should have done better with a poor header that failed to trouble Willy's goal. Swansea were looking particularly potent in attack and the trio of Forbes, Goodfellow and Trundle caused the Premiership side all sorts of problems. The latter was guilty of a huge miss as he found himself past the Blackburn defence and onside, but Friedel made an excellent reaction save with his body to deny last season's top scorer.
At the other end, Shefki Kuki fired a warning when he broke clean through on Willy Gueret's goal, but the Frenchman flew out to smother his effort. However, Swansea did not heed the warning and Blackburn were in front soon after, with Morten Gamst Pedersen taking up an un-marked position in the box to head home the opener.
Blackburn carried the lead into half-time and the 13,000 strong crowd appeared relatively happy with what they had witnessed, with the exception of the home side being one goal down. Welsh International Robbie Savage was booed from the field for an earlier aggressive tackle on Lee Trundle, from which last season's top scorer was lucky to escape unscathed.
Jackett introduced McLeod and Tate for Goodfellow and Austin at the break, whilst the contraversial Savage was replaced by Tugay. Blackburn appeared to immediately step up a gear when the second half commenced and after a number of half-chances, Steven Reid headed home Brett Emerton's cross to make it 2-0.
Newly-signed youngster Tudur Jones replaced Monk, pushing O'Leary back into a defensive role, before Ijah Anderson, Andy Robinson and Brian Murphy were all introduced by the home side around ten minutes later.
Trundle continued to battle away in attack but Swansea's problem appeared to be the quality of the final ball. Britton missed a half chance, before the talisman-like Trundle had a fierce strike blocked by Friedel. However, comedy defending then became the name of the game as Alan Tate's dodgy back-header left Brian Murphy stranded in the Swans goal. Murphy watched on agonisingly as the ball ricocheted off of the post and into the path of a grateful Michael Gray, giving the score-line a somewhat unfair look to it.
Just minutes later though, Andy Robinson pulled one back for the home side after he tricked Brad Friedel with a dangerous free-kick that curled inside the American International's near post, giving the home supporters at least something to smile about. Matt Derbyshire soon wiped those smiles away as he made the most of poor marking to head home the visitors' fourth and round off a good day for Mark Hughes' men.
However, Swansea can take great heart from today's final friendly before the season starts, with 4-1 perhaps reflecting harshly on the South Wales club's performance. The home side could have been a few goals up at half-time and in the end, substitutions and individual errors cost them their unbeaten pre-season record. Goodfellow was lively in his first half perfomance, while Trundle continuted to plug away at the Premiership defence all afternoon. The introduction of Tudur-Jones also suggests that the youngster is set to play a big role in next season's League One campaign.