Nathan Redmond felt Southampton were punished for their mistakes in falling behind at Newcastle, and deprived of any good fortune in pursuit of a route back into the game.
Saints trailed 2-0 after 26 minutes at St James’ Park, before a fine debut goal from Takumi Minamino offered them a lifeline.
But an avoidable third goal on the stroke of half-time left Saints with too much to do, even after James Ward-Prowse reduced the arrears to 3-2 and Newcastle lost Jeff Hendrick to a red card and Fabian Schar to injury.
Danny Ings hit the post and saw a shot cleared off the line, but the nine men held on for victory.
“We’re a bit disappointed in ourselves,” Redmond said. “We gave ourselves a chance in the opening five or 10 minutes, but that lacklustre lapse in concentration, which can happen sometimes, they punished us for that in the first half.
“It’s one of those things we’re looking at – especially on the back of last week – defending as a unit together, as a whole team.
“But this is the Premier League. You can get punished at this level for giving the ball away once – that can cost you.
“In the second half we tried to come out and impose ourselves, be brave and stand up to the challenge, but we were probably just hoping for that little bit of luck to come through in the second half to put us back in the game. If Ingsy’s chance goes in when it's off the post, it’s a different game.
“I feel like we did some good things today and obviously we did some bad things, and we need to assess both of those going into the next game.
“Looking at it fresh straight after the game, as players and myself we're really disappointed to not come away with something, but we've got a strong group that's been together throughout a lot of ups and downs at this club, so we're all sticking together ready for the fight.”