Brentford twice took the lead through Marcello Trotta and Harry Forrester, but Frank Lampard firstly drew Chelsea level before Fernando Torres' late strike spared the holders at Griffin Park.
"They had a lot of play but didn't create clear-cut chances. We defended very well and worked very well against the ball," said Rosler.
"And to be five minutes before the end and leading 2-1, I'm slightly disappointed that we didn't win the game.
"But, overall, my players did fantastically. They earned the right to play at Stamford Bridge.
"It will be a great day for our supporters again, for our players and, financially, it will help enormously.
"Also, congratulations to my players for what they did today individually and collectively. That was top drawer."
Chelsea felt they should have been awarded a stoppage-time penalty when Harlee Dean appeared to handle in the box, but Rosler felt his team earned some good fortune.
"We deserved that luck from what we have put in compared to what Chelsea put in over the 90 minutes," he said.
"There is a football god up there and he is on our side."