Ashley Young assisted a goal on his Inter Milan debut as they were held by Cagliari.
The 34-year-old former England international joined Serie A’s second-placed team for £1.28m from Manchester United last week.
Playing for Antonio Conte’s Inter at right wing-back, he crossed for Lautaro Martinez to head in their opener.
But Radja Nainggolan, on loan from Inter, equalised against his parent club with a long-range deflected shot.
Goalscorer Martinez was sent off in injury time for two quick-fire bookings, the second for dissent.
Young, the first Englishman to play for Inter since Paul Ince in 2007, has now managed more assists in Serie A than the Premier League in the past year.
He failed to set up a league goal in his final 31 appearances for United – a run going back to December 2018.
Inter’s slip-up gives Juventus the chance to extend their lead at the top to six points when they visit Napoli at 19:45 GMT.