"They made it hard for us in the second half but a win's a win and we've got three points on the board".
The 20-year-old was making his first start for the club after a loan spell at Granada. First, his corner was flicked on by Christopher Schindler and inadvertently turned into the net by Palace's Ward. That was until Luiz sprinted onto Morata's pass and volleyed in to bring the nine men to within a goal of Burnley.
"But we're not getting carried away, it's a great result, brilliant for our players and supporters, but we know there's a big season ahead of us, and everyone is telling us it's a big challenge".
Ronald Koeman started all five of his key summer signings here, with Jordan Pickford, Michael Keane, Davy Klaassen, Sandro Ramirez and Rooney all taking their places in the starting XI.
Swansea failed to muster a single shot on target and will be relieved to have escaped with a point against a Southampton side which has now failed to score at St Mary's in 545 minutes.
Dusan Tadic missed a fine early chance to put the home side in front when he guided a close-range finish wide from Ryan Bertrand's inviting cross, and James Ward-Prowse saw an effort deflected over as the home side kept control. And it was weird at half-time because you're three up away at Chelsea and you have to decide how you're going to approach it from there.
But there was no sign on the pitch of Morata's burden when he came on just before the hour mark. Roberto Firmino stepped up to convert the penalty - and then it got even better for Jurgen Klopp's side as they took a 3-2 lead via Salah.
However, there is a sense around Stamford Bridge heading into the new campaign that all is not quite right.
The visitors produced plenty of neat football throughout, but were unable to create much threat and fell behind after 31 minutes when Ahmed Hegazi headed in a Chris Brunt free kick.