Captain Ashley Williams said Wales know they face a tough challenge against Croatia tomorrow night.
"I think they're very good, they've got some top players in their team", the defender warned.
Wales are high on confidence after beating Scotland on Friday, but their last defeat came in October in Croatia.
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Aaron Ramsey has told his English team-mates at Arsenal to beware Wales overtaking them in the FIFA rankings.
Plenty of fine dry weather to come today and prolonged spells of sunshine. A cool easterly breeze will take the edge off the temperatures.
The three-day event in the Welsh capital is expected to attract more than 20,000 visitors.