The Egypt international has often been compared with Barcelona star Lionel Messi.
Messi was in brilliant form against Liverpool, scoring twice after Luis Suarez’s first-half strike, to hand the Spanish champions a massive advantage ahead of the second leg.
Salah had an opportunity to reduce the deficit in the encounter but missed the glorious chance.
“You’re always judged on how you play in the big games, and this week just proved how far he is behind Lionel Messi,” he told the Daily Star.
“Messi never lets you down when it matters. That’s why he’s the best player in the world. Only Cristiano Ronaldo can rival him for that crown.”
Salah currently leads the Premier League goalscorers’ chart with 21 strikes despite a slow start to the season.
Merson is confident that the Egyptian forward will place this failure behind him against Newcastle United on Saturday night.
“I’ve been there. You lie in bed at the hotel after a miss like that and it just keeps on going through your head. It’s a horrible feeling,” he continued.
“But you miss chances sometimes. Everyone does. It just proves he’s human. People say he’s had a bad season but he’s the Premier League’s top scorer!
“He doesn’t seem the type to dwell on it. He seems quite laid back. He could make four mistakes in a game but still not lose his confidence and end up doing something special.
“So I think he will bounce back against Newcastle. He is a strong character and Liverpool need him firing if they’re going to win the league.”
The Pharaohs are in Group A along with DR Congo, Uganda and Zimbabwe.