Evann Guessand scored again late on as under-pressure Oliver Glasner watched his Crystal Palace side beat Zrinjski Mostar 2-0 at Selhurst Park to secure a 3-1 aggregate win in the UEFA Conference League and secure passage into the last 16.
Along with the help of a Maxence Lacroix header Palace now look forward to Friday's draw, where they will find out whether they take on Mainz or AEK Larnaca in the next round.
Back-to-back wins for Palace for the first time since December should guarantee that Glasner remains in position for Palace's trip to Manchester United this weekend after he fanned the flames of speculation around a premature exit this week.
Palace laboured in the early exchanges as they looked to open the scoring and Lacroix's 36th-minute header, teed up by a superb Adam Wharton ball from a set-piece, was their only effort on target in the first period. The goal, though, lifted an otherwise lacklustre Selhurst atmosphere with spots of empty seats reflective of a collective apathy in south London.
While quality was lacking, Palace continued to push a Zrinjski side who had failed to score and therefore win in any of their Conference League games away from home this season.
Ismaila Sarr was denied by opposition goalkeeper Goran Karacic in a one on one as he spurned one of his several chances, as Palace's endeavour proved more than their quality as the game wore on.
However, after Tomi Juric had Palace hearts in their mouths late on as he sent a header wide, Guessand ran through and wrapped up the victory in injury time.
The Conference League last-16 draw will take place on Friday at 1pm UK time in Nyon, Switzerland.
The draw will confirm the last-16 ties and also allocate a side of the bracket for every team so they know who they could potentially meet in the quarter-finals, semi-finals and final.
Each of the play-off winners face the sides that finished in the top eight (seeded teams) in the league phase.
Palace will play the second leg of the tie against either Larnaca or Mainz away from home.
Crystal Palace boss Oliver Glasner played down suggestions of a premature Selhurst Park exit but says he has not enjoyed the backlash during his side's difficult spell.
Speaking to TNT Sports, he said: "I've had 100-per-cent assurance [of staying on]. For me, the number one is the players, the players believing in the staff and I - and that's the most important thing, otherwise you can pack your suitcase and go home.
"They have a great togetherness in the group, the staff and it's the same with the chairman and sporting director.
"They are sometimes wondering - it's the second-best Premier League season ever.
"The best was last year, so maybe the best two in Palace's history, playing European football for the first time, and there is so much noise so sometimes we really don't understand it.
"Maybe I gave some interviews which were not really helpful, I have to admit, but I always say what I am feeling and sometimes it's positive, sometimes it's not so positive.
"That's Oliver Glasner, and in the end, we are in a very good position in the league and now it's up to us with our fans to make a really good season of it."
Zrinjski Mostar boss Igor Stimac says Crystal Palace are his pick to go on and win the Conference League.
"Congratulations to Crystal Palace," he said.
"Looking at the teams which are left there. As far as I'm concerned, they are one of the top three favourites in this competition. I wish them the best of luck to win the competition and to go all the way through."
Quizzed further on who his top three are, Simac added: "Crystal Palace is my favourite. Mainz is the second one. I would say we played against them already. And they have an enormous quality in their team also. They have wonderful support and a really, really well-balanced team. Dangerous from each part, each position."
