Wales must maintain the standard of the 13-6 win against England in their remaining warm-up matches and into the World Cup, says hooker Ken Owens.
Warren Gatland's side were confirmed as World Rugby's top-ranked team after Saturday's win in Cardiff.
The squad are in Turkey for a week's training before facing Ireland twice and starting their World Cup campaign against Georgia on 23 September.
"We have got to be on the money," said British and Irish Lion Owens.
Wales lost 33-19 against England on 11 August, but bounced back to win a tense World Cup warm-up match in Cardiff six days later.
"We've probably had our poor performance out of the system, that slow start people talk about, and we have got to keep building and improving," added Owens.
"We can't let that standard drop."
Victory at Principality Stadium saw Wales overtake New Zealand at the top of World Rugby's rankings for the first time since they were introduced in 2003, but Owens says that will count for nothing unless the side deliver at the World Cup, which reaches its climax on 2 November.
"I would prefer to be there at the start of November, but it is now just a table and something to talk about," he said.
Gatland will name his final 31-man squad for the tournament on 1 September, the day after Wales play Ireland in Cardiff.
And with places in the final party still up for grabs, Owens warns there will be no respite for the players in Turkey.
"I'd like to work on my tan, but that's probably not going to happen," he joked.
"It's a good nine days to get away and get a little bit more training in away from everything.
"We can just concentrate on the rugby again and get our combinations working and get more time on the training field in full rugby situations and hopefully peak for the two games against Ireland to come."
Wales are drawn in Pool D at the World Cup along with Australia, Fiji, Georgia and Uruguay.