Lewis Hamilton hailed his crew of mechanics following a difficult day at the office that he claims left him 'heavily compromised ' ahead of this weekend 's Malaysian Grand Prix . Fresh from an Australian Grand Prix 'triple crown ' of pole position , fastest lap and race win , Hamilton was forced to pull his Mercedes to one side after just four installation laps in the first practice session at the Sepang International Circuit . Mercedes mechanics fix Lewis Hamilton 's car at the team 's garage after its engine failure on Friday . After the car was hauled back to the garage there were initial fears an engine change may be required , only for the fault to lie within the power unit inlet system . The depth of the issue within the system , however , meant Hamilton did not return to the track until 38 minutes into the 90 of FP2 . But the 30-year-old wasted no time in getting up to speed as he went on to set the fastest lap , being the only driver to dip under 100 seconds with a time of one minute 39.790secs . 'It was an amazing job done by my guys to rebuild the car , get the engine and gearbox back on and to get back out , ' said Hamilton . ' I am very grateful for that . Especially here where it is so hot and so difficult for the tyres , so it was really important get back out . ' Hamilton overcame the engine problems in the morning practice session to set the fastest time . Losing too much time , however , may yet prove costly as Hamilton added : 'It affects you quite a bit . 'Fortunately I got a few laps in with a longer run at the end , but in terms of my set-up , I have not made any changes and it is quite a bit off from where we need it . 'Overall , my preparations have been heavily compromised . Whenever you lose a session , and most of the second session too , that definitely does n't help . 'In the end , just to get some laps was crucial . If I had missed all of today then Sunday would be hard . 'Right now I have some improvements to make to the balance and the settings , so I am sure we will tweak and improve it because we have not got the car dialled in . ' But the British world champion says his Malaysian Grand Prix preparations have been 'heavily compromised ' Ferrari 's Kimi Raikkonen was second quickest in both sessions , the Finn finishing 0.373secs adrift of Hamilton 's team-mate Nico Rosberg in FP1 , and remarkably exactly the same time off the Briton in FP2 . Although Ferrari are showing signs of closing in on Mercedes , Raikkonen said : `` The car is still not perfect , but I 'm sure we can improve for tomorrow . 'We have some work to do on the set up to make everything easier , but we 'll do our best and we 'll see where we end up in qualifying . ' Ferrari driver Kimi Raikkonen during practice for the Malaysian Formula One Grand Prix on Friday . Rosberg had to settle for third best , just over four tenths of a second behind Hamilton , followed by Red Bull 's Daniil Kvyat and Williams duo Valtteri Bottas and Felipe Massa . As for ailing McLaren , the returning Fernando Alonso was down in 16th , 2.7secs off the pace , closely followed by team-mate Jenson Button . Alonso , who sat out the first race Down Under as he recovered from concussion suffered in a crash in testing , claims McLaren have progressed from where they were a fortnight ago in Melbourne . The double world champion said : `` It felt great in the car . 'After the gym , the simulator , whatever you do it is not the same as the car , so I enjoyed so much driving here . Fernando Alonso returns to the track after recovering from concussion he suffered in Australia crash . 'It was really the second day of testing for me because I had one good day in Barcelona with 63 laps and then today with 45 laps . 'And the car was much better than expected . The experience we had in winter we had a lot of problems after four or five laps . 'But today we ran 45 laps with zero problems , everything went as we predicted . 'We will see in qualifying where we are , but I think we were 4.6 seconds behind pole position in Australia . 'Here , maybe we could be 3.5 seconds down , so that is a one second or 1.5 second gain in two weeks , so a big step forward . ' Alonso claims McLaren have progressed from where they were a fortnight ago in Melbourne . Manor also hit the track for the first time this season after months of uncertainty and missing Australia due to technical issues despite being present at the Albert Park circuit . Rookie duo Will Stevens and Roberto Merhi completed 34 laps between them , with the Briton 5.9secs down and the Spaniard 7.4secs adrift , with the latter 's day cut short by a spin into the gravel .
Lewis Hamilton missed Friday 's first session and some of the second . Hamilton still set the fastest time in Australia despite the engine failure . The world champion says preparations have been 'heavily compromised ' Fernando Alonso returns to the track following crash in Malaysia .