Fernando Alonso dominated final practice for the Chinese Grand Prix with the Ferrari driver 0.622s faster than anyone else by the end of the session.
Felipe Massa was second fastest after encountering traffic in the final sector of his lap, while Lewis Hamilton was third as Mercedes looked strong again on both soft and medium compound tyres. Sebastian Vettel led Mark Webber as the Red Bulls finished the session fourth and fifth and appeared to struggle towards the end of the lap.
There should still be more to come from Mercedes as Nico Rosberg failed to set a soft tyre lap due to a hydraulic issue and Hamilton backed out of his first attempt at a fast lap, which left his tyres past their best for his timed lap. On the medium compound the Mercedes looked fastest, but the key will be getting them to last as long as possible in the race.
Adrian Sutil was sixth fastest as Force India again looked strong, although team-mate Paul di Resta could only manage 16th. Kimi Raikkonen was seventh fastest but was visibly struggling to keep the rear of his Lotus in check in sectors two and three.
The two McLarens of Jenson Button and Sergio Perez were eighth and ninth as they appear to be on target to meet their goal of making Q3 in qualifying. Perez altered his set-up drastically from Friday after admitting he was not confident with the car in the first two sessions of the weekend.
Nico Hulkenberg rounded out the top ten in the Sauber but could face a challenge for a top ten position from the two Toro Rossos, which impressed in 11th and 12th. Pastor Maldonado was 13th fastest ahead of Rosberg's medium tyre lap, his Williams team-mate Valtteri Bottas and di Resta.
Esteban Guttierrez was again towards the back of the midfield but ahead of Romain Grosjean who complained of a lack of front grip on his soft tyre lap at the end of the session. Jules Bianchi took up his usual position at the head of the backmarkers, 0.3s clear of Caterham's Charles Pic.
Ten minutes into the session an ambulance was deployed in the pit lane to attend to a mechanic at Marussia who sustained a minor injury early in the session.