Lazio pulled a late equalizer as Felipe Caicedo struck late to cancel Ronaldo's opener as Juventus drops points again in a 1-1 draw on Sunday.
Ronaldo had opened after a quarter of an hour in Rome but second-half substitute Caicedo once again proved decisive firing in the equalizer five minutes into injury time.
Juventus missed the chance to move second behind Serie A leaders AC Milan, with the champions three points behind their northern rivals who host Hellas Verona later on Sunday.
Simone Inzaghi's Lazio, currently embroiled in coronavirus chaos, are ninth, five points off the leaders.
Lazio lined out without top striker Ciro Immobile, midfielder Lucas Leiva and goalkeeper Thomas Strakosha, who remain in coronavirus isolation.
The Roman club is being investigated by the Italian football federation for possible COVID-19 violations.
Immobile was among a number of Lazio players blocked by Uefa from taking part in Champions League games against Club Bruges and Zenit Saint Petersburg after testing positive.
But they were included in last weekend's game against Torino, in which Immobile also scored, following negative tests carried out in a lab used by the club.
Inzaghi had been optimistic about them lining out in the Stadio Olimpico but they were left out after they were also reported to have tested positive in another Italian lab.
Lazio midfielder Luis Alberto returned after recovering from coronavirus with the hosts also boosted with defender Stefan Radu back after a month out injury.
Leonardo Bonucci, making his 400th start for Juventus, proved decisive early blocking Vedat Muriqi.
But it was again Ronaldo who proved decisive finishing off a Juan Cuadrado cross after the Colombian shook off defenders Luis Alberto and Mohamed Fares.
Ronaldo, 35, scored his sixth goal in four league games.
Sergej Milinkovic-Savic sent a header wide for the hosts with Joaquin Correa also testing Wojciech Szczesny.
Ronaldo had two chances for a second in the first half, rattling the post, with Pepe Reina tipping a free-kick over the bar.
But with Juventus looking in control, Ronaldo went off with 15 minutes to go after taking a knock to his ankle.
And Caicedo, who had come off the bench nine minutes after the break, once again had the final word.
The Ecuadorian picked up a Correa cross, swiveling to fire in the equalizer to hand Juventus their fourth stalemate in seven league games.