Red Bull-Honda is now "a step closer" to winning the 2020 world championship.
After winter testing, Mercedes appears to still be in a clear lead, but Red Bull has apparently leapfrogged the struggling Ferrari.
"The car does what we expected and what we hoped for," said Marko, Red Bull's top Austrian official.
"We start the season with a very positive feeling. We have come a step closer to our goal of making Max Verstappen the youngest world champion."
However, Marko warned that not too much can be read into the pecking order based on Barcelona testing.
"Testing is deceiving and the teams hide what they really are doing," he said. "But we are certainly much better prepared than in recent years.
"I think we can fight with Mercedes for victory in Australia."
Marko also expressed confidence that reliability will not be an issue, with Honda setting the target of getting through the year without needing to break the three engines per driver rule.
"We assume that the reliability is there," he said.
"We have now done 5000 kilometres on the test bench compared to 500 in the previous year. But the most important thing is that Honda has made a very big step in power.
"We therefore hope that we will be equal to Mercedes and Ferrari, which should mean significant progress in qualifying."
At the very same time, six-time champion Lewis Hamilton says he is "worried" about the spate of engine problems suffered by Mercedes in testing.
"Yes, I'm worried. I would have like to have done more in Barcelona," he said.
"We have quite a few problems to sort out and I don't know how long that will take."