A minor improvement on his best lap - a 1m29.617s for Verstappen.
Verstappen on top ahead of Perez, Alonso, Stroll and Russell.
Stroll moves up to fourth in the Aston Martin to make it a 3-4 for the team.
Gasly moves into seventh for Alpine, 1.1s down on Verstappen.
Verstappen now sets a 1m29.790s, 0.5s clear of the nearest car which is Alonso.
Verstappen, Alonso, Perez, Russell, Hamilton, Sainz, Albon, Leclerc, Stroll and de Vries.
"Struggling for grip. How much time are people finding?"
Verstappen, Alonso, Perez, Russell, Hamilton, Sainz, Albon, Leclerc, Hulkenberg and Magnussen.
The reigning world champion extends his advantage to 0.6s.
He's now 0.4s clear of Alonso at the top of the timesheets.
The Red Bull looks too strong again.
As we reach the halfway point of FP1, Red Bull Racing's @Max33Verstappen is in P1
— Formula 1 (@F1) March 17, 2023
The Dutchman is looking mighty on the street circuit! #SaudiArabianGP#F1pic.twitter.com/F0SfC6VApR
1m30.494s for Verstappen on his second timed lap of the session.
Alonso sets a 1m30.509s - less than a tenth ahead of Perez at the top of the timesheets.
Verstappen goes third with his first lap of the session, 0.9s off Perez.
With 20 minutes gone: Perez, Alonso, Leclerc, Albon, Hamilton, Sainz, de Vries, Gasly, Russell and Norris.
It's a 1m32.262s for Alonso on the softs, 0.2s clear of Perez.
Albon continues to impress with fourth, 0.7s off the pace.
Leclerc and Sainz keep circulating on the hards - 0.5s and 0.6s off Perez's top time on the softs.
No sign of Verstappen so far.
A strong early lap from Perez to go 1.1s clear of Hamilton at the top of the timesheets.
Albon slots into second now, 1.0s off.
Hamilton beats Alonso's benchmark by a tenth.
It's a 1m32.838s for Alonso on the softs, 0.1s ahead of Perez.
Both Ferraris set their first times on the hards.
Perez, Leclerc, Sainz, Tsunoda, Norris, Sargeant, Magnussen, Bottas, Hulkenberg and Russell.
Perez makes the most of the softs to smash the current benchmark by 1.4s.