"Jejich tým ještě nikdo neporazil."

Translation: No one has defeated their team yet.

[rosemarie45933]

"No one has yet defeated their team". This translation is also semantically correct and should be accepted

[VladaFu]

added

[BoneheadBass]

I would agree that your version is fine, though MAYBE used less frequently. You might report it, if you haven't already done so.