Unlike in Great Britain however, the leading margin ahead of his rival Casey Stoner in the first practice was a little over one hundredth of a second, as the two riders battled through the Friday action until the very last lap.
Once they both got up to speed, the lead between them exchanged several times, until Lorenzo made the best of it on his last lap with the best time of 1:35.169. The Ducati rider made a late effort to dethrone the Spaniard from 1st place, but had to settle for the runner-up spot, some 0.011 seconds behind.
The two riders lapped the Assen circuit in a league of their own, as 3rd placed Nicky Hayden (Ducati) finished the 90-second session more than half of second behind Lorenzo. The Yamaha-Ducati sandwich was completed by 4th placed Colin Edwards (Tech 3), who managed to finish ahead of Honda duo Andrea Dovizioso and Dani Pedrosa.
British GP podium finisher Ben Spies had some troubles getting his bike to competitive pace on Thursday afternoon and had to settle for 8th place, being passed by fellow rookie driver Aleix Espargaro (Pramac Ducati). The American driver did manage to outlap Gresini duo Marco Simoncelli and Marco Melandri inside the Top 10 though..
Here is how the first practice of this weekend's Dutch GP at Assen ended:
1. Jorge Lorenzo (Yamaha) 1:35.169
2. Casey Stoner (Ducati) 1:35.180
3. Nicky Hayden (Ducati) 1:35.686
4. Colin Edwards (Tech 3 Yamaha) 1:35.699
5. Andrea Dovizioso (Honda) 1:35.868
6. Dani Pedrosa (Honda) 1:35.922
7. Aleix Espargaro (Pramac Ducati) 1:35.927
8. Ben Spies (Tech 3 Yamaha) 1:35.942
9. Marco Simoncelli (Gresini Honda) 1:36.002
10. Marco Melandri (Gresini Honda) 1:36.269
11. Randy de Puniet (LCR Honda) 1:36.294
12. Hector Barberta (Aspar Ducati) 1:36.735
13. Loris Capirossi (Suzuki) 1:36.786
14. Mika Kallio (Pramac Ducati) 1:37.261
15. Alvaro Bautista (Suzuki) 1:37.384
16. Kousuke Akiyoshi (Interwetten Honda) 1:41.332