The former Liverpool forward scored twice in the opening 10 minutes before another strike in the 72nd for his treble sealed the three points for the newly-promoted team.

Al-Ahli and Al-Hazm were two of the four clubs promoted to the Saudi top flight, which has increased from 16 teams to 18 this season.

The hosts took the lead after six minutes with a header from captain Firmino, who got his double with a close-range finish from ex-Manchester City winger and fellow new arrival Riyad Mahrez's cross four minutes later.

Having been largely dominated in the first half, Al-Hazm pulled a goal back five minutes after the break as Vina seized on a poor clearance by goalkeeper Edouard Mendy, signed from Chelsea.

Firmino, however, capped a perfect opening night by restoring the two-goal lead with less than 20 minutes to go.

Reigning champions Al-Ittihad, who have signed Ballon d'Or winner Karim Benzema from Real Madrid and Chelsea midfielder N'Golo Kante, play their first game on Sunday at Al-Raed.

Cristiano Ronaldo's Al-Nassr, runners-up last season, face Al-Ettifaq on Monday. The game could see former Liverpool teammates Sadio Mane, who joined Al-Nassr last week, and Jordan Henderson facing off.