The Real Madrid star played alongside Bale during his time at Tottenham and is wary of the threat that his former teammate poses to Croatia.
"Can we stop Gareth? We must, because these are three very important points," Modric told the Daily Mirror. "The win against Serbia would ultimately mean a lot less if we do not beat Wales. One player can't win games by himself and we know that we will be up against a good team who will be roared on by a passionate home crowd."
Wales is looking to reduce the gap between itself and second-placed Croatia to four points with a win at the Liberty Stadium and is on good form following a 2-1 victory over Scotland on Friday.
Chris Coleman’s side lost Bale midway through the game but rallied to win. Despite the winger's obvious importance to the team, Coleman believes it can win without the him.
"I can understand why people look at the fact Gareth went off and say it could be the end of our hopes, but we don’t feel that within the group," Coleman added. "When we beat Scotland 2-1 in Cardiff it was different circumstances because we won late on. But the performance in Glasgow was much more mature and rounded – and half of it was without 'Baley'.
"We mustn't forget how good he is and, with him, of course the team is stronger. But the players have to take great confidence from that. Sometimes we won't have him so we need others to step up to the plate and that's what happened in Scotland. Everyone stepped up and it was a tremendous performance. Hopefully they can step up again. But we won’t get carried away as Croatia is a huge game and another big test for us."