July 11th, 2018 - 20:00 CET (14:00 EDT)
Luzhniki Stadium, Moscow (Capacity 78,011)
This is the same location as the Final so if Croatia advances they will stay in place and be familiar with the grounds for the Final.
Head to Head comparison:
Betting odds from OddsChecker.com:
Odds from FiveThirtyEight.com has Croatia advancing to Finals at 43%: