Pol Espargaro, winner of the last two 125cc races, kept the pressure on early title leader Nicolas Terol by leading Friday practice for the Italian Grand Prix.
The Tuenti Derbi rider spent much of the hour on top, but was toppled by Terol with just a few seconds remaining. Espargaro then pushed hard on his last lap to regain P1 by 0.058sec from the Aspar Aprilia rider.
Terol, winner at Qatar and then second to Espargaro at the last two events, starts round four with a slim two-point lead over his fellow Spaniard.
Terol's team-mate and 2009 Mugello winner, Bradley Smith, began the weekend with third position, but was 0.650sec from Espargaro.
Espargaro's team-mate Efren Vasquez and Molenaar Aprilia's Randy Krummenacher set the exact same time in fourth and fifth, while the top Italian was 16th fastest Luigi Morciano!
Friday practice - Mugello:
1. Espargaro (Derbi) 1m 59.373s
2. Terol (Aprilia) +0.058s
3. Smith (Aprilia) +0.650s
4. Vazquez (Derbi) +0.845s
5. Krummenacher (Aprilia) +0.845s
6. Marquez (Derbi) +0.861s
7. Rabat (Aprilia) +1.022s
8. Cortese (Derbi) +1.052s
9. Koyama (Aprilia) +1.185s
10. Folger (Aprilia) +1.924s
13. Webb (Aprilia) +2.165s