Wales coach Warren Gatland was left ruing his side's ill-discipline after falling to a 29-17 World Cup quarter-final loss to Argentina in Marseille on Saturday.
Emiliano Boffelli's 19 points from the kicking tee, allied with tries from Joel Sclavi and Nicolas Sanchez, were enough to see Los Pumas past a Wales side for whom Dan Biggar and Tomos Williams crossed for tries.
Biggar, playing his 112th and final Test, added seven points with the boot before coming off five minutes from time.
"They are a tough team to put away and they hung in there with some fight," Gatland said of Argentina, who qualified for the quarter-finals as runners-up to England in Pool D and will now take on either Ireland or New Zealand in the semi-finals.
"It was an incredibly tough Test match that could have gone either way. We had opportunities to win the game."
Gatland added: "We spoke about how important discipline was and it kept them in the game and the scoreboard ticking over.
"If you don't take your chances and keep the scoreboard ticking over, they'll come at you.
"They defended well. I thought they were a bit out on their feet before half-time but a couple of penalties allowed them back into the game. That for me was a bit disappointing, those couple of soft penalties.
"We went into the game with a lot of confidence... it's not to be, but that's sport. It's the way Test match rugby goes."
- One that slipped away -
Gatland said the team were "all pretty gutted", saying it had been "a missed opportunity" to advance into the last four.
"It's one that slipped away from us. You've got to take learnings away from it," said the Kiwi, in his second tenure as Wales coach after a highly successful first spell from 2007-19.
"We've got a game against the Barbarians (on November 4) and then we'll focus on the Six Nations, we just make sure we don't take a backwards step."
Co-captain Jac Morgan called the result "devastating".
"We knew they were going to be a physical team but discipline and a couple of errors let us down," the flanker said.
"We let them into our half and they capitalised on that. We let them have more possession and they got points out of it.
Dewi Lake, the other co-captain, added: "We're gutted as a group from missing out on the final four, all the work we've done over the past four months to get to this point.
"At the start of the campaign not many people thought we'd get out of the group and we came into this game as favourites.
"Full credit to Argentina. They left everything out there as did we but our accuracy let us down a bit."
Gatland took over as coach for the second time with Welsh rugby in disarray, with turmoil between the union and regional clubs, alongside a raft of off-field problems.
But he transformed a losing team into one that won all four of their Pool C games and Gatland insisted that that was a positive to take away from the team's French adventure.
"They should hold their heads up, they should be proud of what they've done," he said of the Welsh players.
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