(CNN) -- Champion elect Sebastian Vettel recorded the fastest time in practice Friday for the Japanese Grand Prix during an afternoon session overshadowed by the news of the death of Maria de Villota.
Red Bull's Vettel will win his fourth straight world title Sunday if he wins at Suzuka and nearest rival Fernando Alonso finishes outside the top eight.
Vettel showed his car's pace with a one minute 33.852 clocking in hot conditions, with teammate Mark Webber of Australia second fastest.
But the thoughts of the drivers were with de Villota, a reserve driver for Marussia until a horror crash in testing a year ago curtailed her F1 ambitions.
Alonso struggled to 10th best after a spin in his Ferrari, but then paid tribute to his fellow Spaniard de Villota.
"I still can't believe it and need a while to stop and think about it," he told the official F1 website.
"Of course, it's very sad news for the world of motorsport as Maria was loved by everyone. Now, all we can do is pray for her and for her family."
Jenson Button, ninth best for McLaren spoke for many: "Today's news about Maria de Villota is horrendous and tragic.
"This is a real shock to the whole Formula One 'family' and the world of motorsport. My thoughts are with her family at this time."
Vettel, who has won the last four Grand Prix races to open up 77 point lead over Alonso, cautioned against placing too much emphasis on Friday practice.
"It's good to see we are up there today, but it's not always so important," the German said.
"We need to step up our game for tomorrow, as Mercedes will be strong in qualifying."
Nico Rosberg in a Mercedes was the closest challenger to the Red Bulls with the third fastest time with teammate Lewis Hamilton back in sixth.
Hamilton had been quickest in morning practice ahead of Rosberg.
Separating them in the afternoon were the Lotus duo of Kimi Raikkonen and Romain Grosjean, with the former also ending in the gravel after a spin on Turn 7 of a testing circuit.
Saturday will see the third practice session ahead of final qualifying.
If results go Vettel's way, he will emulate the feat of fellow German Michael Schumacher and Argentina legend Juan Manuel Fangio in claiming four straight F1 crowns.