Williams` Felipe Massa was fastest as McLaren`s embryonic relationship with engine supplier Honda suffered another blow on the first day of the third pre-season test in Barcelona on Thursday.
Massa completed more than 100 laps with his best time of 1min 23.500sec the quickest of the day ahead of Sauber`s Marcus Ericsson.
World champion Lewis Hamilton was third fastest despite also failing to run in the afternoon session due to a MGUK failure in the Mercedes engine.
Jenson Button managed just seven laps in the McLaren before lunch as the Woking-based team`s struggles for reliability less than a month before the first Grand Prix of the season were again exposed with a hydraulic leak which brought their day to an early end.
With three days of testing remaining, McLaren have managed just 210 laps, well under half of the mileage completed by every other team on the grid bar Force India, who hope to unveil their new JVM08 car for the first time on Friday afternoon.
McLaren chief executive officer Ron Dennis insisted that he expects two-time world champion Fernando Alonso to be fit for the Australian Grand Prix on March 15 despite missing this test after spending three nights in hospital due to a crash in the second test last weekend.
Results from day one of the third pre-season test in Barcelona:
1. Felipe Massa (BRA/Williams) 1:23.500 (103 laps)
2. Marcus Ericsson (SWE/Sauber) 1:24.276 (122 laps)
3. Lewis Hamilton (GBR/Mercedes) 1:24.881 (48 laps)
4. Daniil Kyvat (RUS/Red Bull) 1:25.947 (75 laps)
5. Romain Grosjean (FRA/Lotus) 1:26.177 (75 laps)
6. Kimi Raikkonen (FIN/Ferrari) 1:26.327 (80 laps)
7. Carlos Sainz Junior (ESP/Toro Rosso) 1:26.962 (86 laps)
8. Jenson Button (GBR/McLaren) 1:31.479 (7 laps)