Alexander Geynrikh (14), Renat Bayramov (24), Shahboz Erkinov (38) and Server Djeparov (68) scored goals as the defending champions reached 41 points.
Neftchi were held 0-0 by Kuruvchi in a match between the second and third teams in the league. Kuruvchi are five off the pace, followed by Mashal, who lost to Samaraqand 2-1, on 32 points.
In other matches, Andijan drew with Nasaf 4-4 in an eight-goal thriller, Kyzylkum lost to Shurtan 1-2, Navbahor beat Traktor 2-0, Tupalang drew with Vobkent 0-0 and Bukhara edged Metallurg 2-1.
STANDINGS: 1. Pakhtakor 41, 2. Neftchi 38, 3. Kuruvchi 36, 4. Mashal 32, 5. Kyzylkum 28