In Singapore, Lance Stroll and Sebastian Vettel finished sixth and eighth, propelling the team from ninth to seventh in the constructor’s championship, ahead of Haas and AlphaTauri.
Then, during the rain-interrupted Japanese Grand Prix, Vettel put in a storming drive to sixth after winning a final-lap tussle with Fernando Alonso, edging the team closer to Alfa Romeo in the constructors’ battle.
The gap to the sixth-placed Swiss outfit has tumbled from 27 points to seven points in just two races.
Krack acknowledged the recent results have been a confidence booster for the whole team, but he insisted that it needs to keep its game up in all areas.
“Confidence is not everything, you also have to have a quick car,” he told Autosport when asked about the impact of the last two events. “Because with confidence alone, we don't do much.
“We know where we are with our car, we have made some steps over the year. But still, in a regular race, we will struggle to finish sixth.
“We need to stay realistic. There's four more to go. If we manage to score, or to continue scoring, there's a chance that we can still grab a position.
“But the situation can also turn quickly. If one of the rival teams are scoring significantly, then also we could lose a position.
“It's four races, it's still long, and we need to really keep our game up. But certainly, I think in the 12 last races, we have scored 10 times. I think you can see that we are on a good progression.”
In Suzuka Vettel spun to the back of the field after first lap contact with Alonso, and a decision to pit for inters when the green flag flew at the race resumption was the key to his jump up the order.
The only other driver to make that call was Nicholas Latifi, and crucially Vettel got out of the pits in front of the Williams, who finished the race in ninth place.
“We had spoken about it, we had time to discuss this, how are we going to approach it,” said Krack about the strategy.
“And then we decided that together. Ultimately, the driver had to make the final call, because we don't see all the track conditions.
“From that point of view, he had his final call. We were ready. And I think this was key, but also key was that we could pass Latifi on the pitstop, because without that, we would not have ended in front of Fernando. Basically these two decisions were key.”
Looking to the season run-in, Krack says while the remaining four venues of the year are very different to those where the team has scored well this year, he remains hopeful.
“The next races they are all very similar, in terms of characteristic. They are not the kind of Baku, Singapore and Monaco track. So it will be more difficult for us than the ones I mentioned.
“We could have rain in Sao Paulo, we have a sprint in Sao Paulo as well. So there are still some opportunities.
“There is no track now that is upcoming where we think it would be really bad for us. So let's see.”
