The Bianconeri were beaten by Lazio for the second time this season on Saturday, falling 2-1 at home after conceding two goals to Ciro Immobile just like in the Italian Super Cup in August.
It’s the second straight match that Juventus have dropped points after drawing with Atalanta 2-2 shortly before the international break.
‘We need to work on our lapses in concentration,’ Juventus coach Massimiliano Allegri said.
‘To win the title you’ve got to fight and work for it every day.
‘We fought but only in segments. At other times we were too loose.’
Lazio moved level with Inter Milan and Juventus in the standings, two points behind leader Napoli, who later visited Roma and took the chance to create a five-point advantage with a 1-0 victory.
Inter now face AC Milan in the Milan derby on Sunday.
‘The lads should enjoy this achievement,’ said Lazio coach Simone Inzaghi, who is mooted as an eventual replacement if Allegri leaves Juventus.
‘At the start of the season they said we would finish ninth or 10th. Now people should be talking about us.’
Juventus led 1-0 at halftime courtesy of a rebound goal from Douglas Costa but experienced defenders Giorgio Chiellini and Andrea Barzagli couldn’t contain Immobile after the break.
Substitute Paulo Dybala came close to rescuing Juventus but was denied first by the post in stoppage time then had a penalty blocked by Lazio goalkeeper Thomas Strakosha at the final whistle.
Immobile had no such trouble.
Two minutes into the second half, Luis Alberto set up Immobile to finish a counterattack with a confident, low, angled shot.
Five minutes later, Immobile was at it again in a virtual replay, only this time goalkeeper Gianluigi Buffon charged forward and tripped the striker to set up a penalty.
Immobile drilled his spot kick to the right corner as Buffon went the other way.
Immobile leads the Serie A scoring chart with 11 in eight matches and also has the best tally in Europe’s top five leagues with 15 in all competitions for Lazio.