Spaniard Checa set a best time of a minute 55.307 seconds, almost half a second quicker than that of Italian Giugliano.
Briton Tom Sykes was also half a second off the pace in third on his factory Kawasaki with Ireland's Eugene Laverty fourth on the Aprilia.
Sykes's compatriot Leon Haslam was fifth while his BMW Motorrad Motorsport team-mate Marco Melandri, the championship leader, was down in 12th.
Aprilia Racing's Max Biaggi, second in the standings just 18.5 points behind Melandri (308.5), was sixth ahead of a trio of Britons in Jonathan Rea (Honda), Leon Camier (FIXI Crescent Suzuki) and Chaz Davies (ParkinGO MTC Racing).
Every manufacturer therefore has at least one rider on the front two rows of the provisional grid.
Sykes is third in the championship with 267.5 points ahead of Checa (233.5), Rea (212.5), Haslam (180) and Laverty (173.5).
Results (times/laps)
1 66 T. SYKES GBR Kawasaki Racing Team Kawasaki ZX-10R 1'54.966 16
2 3 M. BIAGGI ITA Aprilia Racing Team Aprilia RSV4 Factory 1'54.969 15
3 65 J. REA GBR Honda World Superbike Team Honda CBR1000RR 1'55.073 16
4 33 M. MELANDRI ITA BMW Motorrad Motorsport BMW S1000 RR 1'55.233 16
5 91 L. HASLAM GBR BMW Motorrad Motorsport BMW S1000 RR 1'55.385 14
6 2 L. CAMIER GBR FIXI Crescent Suzuki Suzuki GSX-R1000 1'55.586 16
7 58 E. LAVERTY IRL Aprilia Racing Team Aprilia RSV4 Factory 1'55.742 16
8 7 C. CHECA ESP Althea Racing Ducati 1098R 1'55.783 16
9 19 C. DAVIES GBR ParkinGO MTC Racing Aprilia RSV4 Factory 1'55.905 16
10 34 D. GIUGLIANO ITA Althea Racing Ducati 1098R 1'56.013 13
11 76 L. BAZ FRA Kawasaki Racing Team Kawasaki ZX-10R 1'56.197 18
12 21 J. HOPKINS USA FIXI Crescent Suzuki Suzuki GSX-R1000 1'56.626 13
13 4 H. AOYAMA JPN Honda World Superbike Team Honda CBR1000RR 1'56.721 17
14 121 M. BERGER FRA Team Effenbert Liberty Racing Ducati 1098R 1'56.931 14
15 84 M. FABRIZIO ITA BMW Motorrad Italia GoldBet BMW S1000 RR 1'56.940 13
16 50 S. GUINTOLI FRA PATA Racing Team Ducati 1098R 1'56.975 8
17 87 L. ZANETTI ITA PATA Racing Team Ducati 1098R 1'57.089 14
18 59 N. CANEPA ITA Red Devils Roma Ducati 1098R 1'57.115 9
19 86 A. BADOVINI ITA BMW Motorrad Italia GoldBet BMW S1000 RR 1'57.142 16
20 44 D. SALOM ESP Team Pedercini Kawasaki ZX-10R 1'57.214 15
21 57 L. LANZI ITA Liberty Racing Team Effenbert Ducati 1098R 1'57.599 12
22 5 A. LUNDH SWE Team Pedercini Kawasaki ZX-10R 1'57.775 18
23 68 B. MCCORMICK CAN Team Effenbert Liberty Racing Ducati 1098R 1'58.760 16
24 64 N. BRIGNOLA ITA Grillini Progea Superbike Team BMW S1000 RR 1'59.863 14
