The Chelsea number one has impressed in his first season in the Premier League, having previously caught the eye in La Liga and the Champions League during a prolonged loan spell at Atletico Madrid.
In fact, Courtois replaced De Gea at Atletico when the Spaniard joined Manchester United in 2011, and as far as Schwarzer is concerned, his former teammate is by far the better of the two.
“For me, it’s Thibaut Courtois,” he said when asked who was the better of the pair.
“He’s performed extremely well. He’s come in and replaced Petr Cech, who’s been phenomenal at the club, is a legend and has won everything.”
The goalkeeper, who now plays for Leicester City after a move earlier in the season, says the manner in which the Belgian has adapted to the Premier League shows he is the better player.
Courtois has settled immediately in England to establish himself at Stamford Bridge ahead of rival Petr Cech. In contrast, De Gea initially struggled during his first season at Old Trafford, with many labeling him a flop at the time.
He has since improved to become arguably one of the league’s top keepers, but Schwarzer says the difference in that initial settling in period is key in determining who is better.
“Even in the short time he’s been playing in the Premier League, he’s shown how well he can adapt,” he added.
“Coming from La Liga to the Premier League is a huge step and you saw with David de Gea how difficult he found it in his first season. Courtois has taken it in his stride though.”