Chris Boyd reflected on a 'bittersweet' afternoon for his Saints side after they lost 40-21 to Exeter Chiefs at Sandy Park.
The Chiefs, who finished the Gallagher Premiership regular season top of the table, scored 19 unanswered points during the second period to earn a bonus-point success.
Saints had gone ahead twice early on, through Piers Francis and Rory Hutchinson, and they levelled it at 21-21 thanks to another stunning Cobus Reinach intercept score.
But the Chiefs eventually pulled away to secure the success.
However, thanks to Wasps' 27-25 win against Harlequins at the Ricoh Arena, Saints finished fourth courtesy of having won one more game than Quins this season.
And Boyd will now take his team back to Sandy Park for a Premiership play-off semi-final next Saturday (kick-off 4.30pm).
"It's bittersweet really," Boyd said.
"We're obviously disappointed with the scoreline and with the way we conceded some of that territory, pressure and points.
"But it's fantastic that for the first time since 2015 we've managed to get ourselves into a Premiership semi-final.
"We come back here to play these guys and there's no surprises or secrets - we know what we're going to have to deal with and we're going to do our best to do that.
Boyd added: "The power came on from them in the last 15 minutes of that first half.
"We controlled the first 25 minutes and didn't let them get into the game.
"They got into the game through our errors and ill-discipline. They scrum you to death, put it to the corner and so it goes on.
"We beat them at home at Christmas time with a really good, disciplined and accurate performances. If we're not disciplined and accurate next week, we'll come here and get a spanking.
"But if we get our game right, we're in with a chance.
"We've got to play our game and we have to have the ball to do that.
"We've got to be better off the source of ball that we'll get."
Saints turned to their bench in the second half to give some players a breather, with Cobus Reinach and Piers Francis appearing to suffer knocks.
But Boyd does not believe those issues are serious and his main concern is about Reece Marshall, who was forced off after just five minutes with a left leg injury.
"We might have just about cut that (the replacements) a bit tight," Boyd said.
"At one stage, Wasps were up 24-8 with 15 minutes to go and I thought we could get a few guys off, particularly in Dan Biggar's case, but it might have been a bit tight.
"Most of the ones who went off are bumps and bruises but obviously the biggest concern is Reece Marshall. We're a little thin in that hooker space."