Roma lost 2-1 at AC Milan to leave it at risk of missing out on second place in Serie A, while Paul Pogba marked his comeback with a goal as newly crowned champion Juventus drew 1-1 against relegation-threatened Cagliari on Saturday.
Marco van Ginkel and on-loan Roma forward Mattia Destro gave Milan a comfortable lead until Francesco Totti set up a nervy finish with a disputed penalty.
"We lacked efficiency and played at too low a tempo, which is a handicap for such an important match," Roma coach Rudi Garcia said. "Now we have three matches left and we have to change our tempo if we want to reach our target. They are three finals and we have to realize that."
Roma remained provisionally second — in the Champions League spot — with a one-point advantage over city rival Lazio, which hosts Inter Milan on Sunday. The two capital teams meet in the penultimate match of the season.
Napoli is five points behind Roma in fourth, and visits Parma on Sunday. It faces Lazio in the final round.
In Turin, Juve coach Massimiliano Allegri rested almost all his stars ahead of Wednesday's Champions League semifinal at Real Madrid. Pogba opened the scoring on the stroke of halftime, 52 days after a right-thigh muscle tear.
Luca Rossettini leveled five minutes from time to give Cagliari a crucial point, tapping home the rebound after his header from a free kick came off the left upright. The Sardinian side moved to within five points of safety, with 17th-place Atalanta visiting Palermo on Sunday.
Roma climbed back into second with two successive wins, and it almost went in front of Milan in the 17th minute when Kostas Manolas headed Alessandro Florenzi's corner off the right post, and Davide Astori turned the rebound wide.
It was Milan which took the lead five minutes from the interval as Keisuke Honda broke down the right flank before crossing for Van Ginkel to sidefoot home from close range for his first goal since joining on loan from Chelsea in January.
Honda was also involved in Milan's second goal just before the hour mark, crossing for Destro to head home against his former club. While he will probably return to Roma at the end of the season, Destro celebrated the goal which could end Roma's chances of a second-place finish.
Roma was handed a way back into the game in the 72nd when Juan Manuel Iturbe collided with Nigel de Jong in the area, and Totti converted a poor penalty, which just squeezed under a diving Diego Lopez.
It was Milan's first win in six matches.
There was a party atmosphere at Juventus Stadium, with the team having clinched its fourth successive title at Sampdoria last weekend. The fans sang throughout and waved flags provided by the club.
"It was a wonderful day and it was inevitable I'd feel a bit emotional as well, I'm certainly not made of iron!" said Allegri, who won the title with AC Milan in 2011, before being sacked by the Rossoneri in January last year. "It is an important achievement for me, it's now two titles with two different clubs. It was a special day.
"Paul put in a decent display, he's in good physical condition. It was important for him to regain his judgment of distances in the middle of the pitch. It's a pity we didn't win the game but the lads did well and it wasn't easy, seeing as certain players hadn't featured for a while."
Juventus was full of confidence after Tuesday's 2-1 win over Madrid, which left it with all to play for in the second leg.
Gianluigi Buffon, Giorgio Chiellini, Leonardo Bonucci, Stephan Lichtsteiner, Fernando Llorente and Alvaro Morata were among those kept on the substitutes' bench. Key playmaker Andrea Pirlo watched from the stands along with league leading goalscorer Carlos Tevez.
Romulo also made his comeback from injury, with his last appearance coming in November's 7-0 win over Parma.