Williams race engineer Dave Robson believes the British outfit improved the performance of its 2019 car in Barcelona, but isn't sure the progress will show on the challenging streets of Monaco.
Williams had expected a step forward at the Spanish Grand Prix thanks to a series of updates implemented on the team's FW42.
While George Russell and Robert Kubica were nowhere near a top-ten finish at the Circuit de Catalunya, slight improvements were recorded according to Robson.
"Following the race and test in Barcelona, we believe that we have improved the performance of the FW42 and increased our understanding of the car and the tyres," said Williams' senior race engineer.
"Whether this will show or not in Monaco is unclear due to the unique nature of the Monte Carlo circuit and unpredictable local climate.
"However, we look forward to the challenge of Monaco knowing that we will need to make some changes to the car to suit this circuit and knowing how important it is to develop the drivers’ confidence over the course of the weekend.
"We also know that Monaco can spring a few surprises and we will be ready to use our excellent reliability and pit stop performance to exploit any opportunities that arise."
Russell's previous experience of racing in the Principality dates back to last year in Formula 2, although its wasn't the young Brit's best race weekend during his 2018 championship-winning campaign.
"Monaco is a very iconic circuit and place on the Formula One calendar," said Russell in the team's preview.
"It will be a privilege to drive around the streets once again. Last year in Formula 2 was my worst weekend of the year, so I hope to make a better job of it this year."
As for team mate Robert Kubica, the Pole's return to Casino Square could prove challenging for a driver who practically drives with one hand.
Still, the 34-year-old is looking forward to be set loose once again in Monaco.
"I remember the streets to be narrow, and now the cars are wider and much bigger, it will be tough," he admitted.
"It is a special race, one very different to the others on the Formula One calendar.
"Already this year, we have had a street circuit race in Baku with close walls and barriers, but Monaco has different characteristics and I look forward to driving there."