Real Sociedad ensured Valencia's stay in the top four was a brief one as they registered a crucial victory at Sevilla.
Sociedad won 2-1 in Seville to reclaim the advantage in the race for the final Champions League spot in Spain.
Ivan Rakitic put Sevilla ahead in the 10th minute but he turned from hero to villain seven minutes later with a headed own goal.
Imanol Agirretxe then scored what turned out to be a winner with Sevilla then having unused substitute Jose Antonio Reyes given a straight red card and sent from the bench.
Earlier in the evening a solitary goal by Jeremy Mathieu was enough for Valencia to see off Getafe 1-0 in Madrid.
The French centre-back struck just before half-time to give the visitors the lead in what was a largely uneventful match at the Coliseum Alfonso Perez.
The result means Getafe missed an opportunity to gain ground in their bid to qualify for the Europa League and remain in ninth place in the table.
Elsewhere, Granada took a huge step towards securing their La Liga future with a 3-0 victory over fellow strugglers Osasuna.
Youssef El Arabi's 23rd-minute goal gave Granada the lead and victory was all but secured when Fernando Nano felled Yacine Brahimi in the penalty area with 10 minutes remaining.
Nano saw red and Guilherme Siqueira's cheeky dinked penalty wrapped up three vital points, before Diego Buonanotte added gloss to the scoreline late on.
The win sends Granada seven points clear of the relegation zone but Osasuna will be looking anxiously over their shoulders, especially with a final-day clash with Real Madrid awaiting them.
Eder, Lorenzo De Silvestri and Mauro Icardi maintained the Blucerchiati's excellent record against the dominant force of Italian football after Fabio Quagliarella had put Antonio Conte's side in front.
Emmanuel Giaccherini added a second late on for Juve, but they were left still waiting for their first win again the Genovese club in four years.
Juve also missed the chance to have beaten every single opponent in Serie A at least once this season.
Things looked to be going well for Juve when Andrea Pirlo sent an excellent first-time ball from the halfway line over the Samp defence into the path of Quagliarella who kept his cool to thread the ball inside the near post with Angelo Da Costa getting a hand to the ball.
The former Samp striker did not celebrate out of respect for his ex-colleagues.
Juve's lead lasted little over five minutes before a foul by Giorgio Chiellini on Icardi inside the area saw a penalty awarded.
Eder stepped up to beat Marco Storari and bring the Blucerchiati level.
De Silvestro gave Samp the lead with his second goal in as many games, leaving Storari no chance with a bullet header at the near post from a corner.
Quagliarella should have brought Juve back on terms, but his shot from six yards was straight at Da Costa in the 70th minute.
Five minutes later, a burst of pace from former Juve winger Marcelo Estigarribia saw him race away from the last Juve defender before sliding the ball across the slick surface to Icardi, who could not miss the open goal from just a yard out.
The referee then awarded Juve a penalty only to change is mind after conferring with his assistant behind the goal, much to Chiellini's annoyance.
Nicklas Bedntner was sent on by Conte, but his evening did not last long as he landed badly on his arm, leaving the field and leaving Juve with 10 men as all three substitutions had been made.
The Serie A champions still did not give up the fight, though, and Giaccherini sent a shot into the top right-hand corner of Da Costa's goal in the first minute of stoppage time.
Juve were unable to find an equaliser, though, as they slipped up once again to their bogey side for their fifth defeat of the season.
