Which sentence is acceptable, or both?

[roseriver1012]

What they wanted to do was win the game.

What they wanted to do was to win the game.

Which sentence is acceptable? or both? Thanks for help!

 

[probus]

No preference. They are both fine.

 

[roseriver1012]

No preference. They are both fine.

What if there is no "do" in the subject sentence?

What they wanted was win the game.

What they wanted was to win the game.

Will both of them be fine?

 

[Islands]

Only this one is correct.
What they wanted was to win the game.