Vettel, who sits 10th in the drivers' standings going into the British Grand Prix, will leave Ferrari at the end of the current campaign.
The pair collided on the opening lap of the second race in Austria, the Steiermark Grand Prix, with both retiring.
"It's a mystery where Leclerc got that speed from", Marko says to Auto Bild. "He was faster on the straights than we were, but that only seems to be the case with him". We tried it but we were not very confident about making it.
"I definitively didn't not expect to get P4 today, so it's great and I'm very, very happy".
"Obviously not ideal for myself, not a good session", Vettel said.
"A little bit (worried about race pace), but we changed the vehicle a little bit from yesterday - I don't think it affected it much for qualifying, looking at the result, but hopefully that will improve the race pace". "I struggled to make the vehicle work".
After a disrupted Friday - Vettel missed P1 completely and then had a brake pedal issue in P2 - the four-time world champion was already on the back foot heading into qualifying and while he did make it into Q3, he qualified only 10th and will have to start the race on the soft tyre. "The vehicle was not too bad but it didn't fit me today".
Team mate Charles Leclerc meanwhile put his vehicle on the second row, in fourth place. Struggling yesterday with very little laps, and this morning to get into the rhythm. "We have to start with the soft, which is probably not good news, but we try to make it work and go from there". Nevertheless I'll try everything I can tomorrow and we'll see what we can do.