Cesc Fabregas gave the Blaugrana an early lead, but Espanyol eventually restored parity in the 86th minute via Alvaro, much to the frustration of Busquets.
"We were having a difficult time at the end of the first half, because they had clear chances. In the second half we were better than Espanyol, but they drew level," Busquets told the club's official website.
"We had opportunities to win, but in the end it didn’t work out that way. Even though we deserved more, we were up against a difficult rival and we can’t do anything about the result now."
The stalemate, coupled with Real Madrid's 5-1 win over Granada on Saturday, saw Barca fall five points behind their arch-rivals at the top of the table, but Busquets believes that the league title is far from settled.
"There’s a lot of La Liga left. It’s evident that it’s better to be ahead than behind, but that’s that. Let’s see if we can cut into their lead. We must keep on working."
Barcelona sit second in the league table with 38 points from 17 games and they play host to Real Betis this Sunday.
Starting in November and continuing through January, Goal.com is publishing exclusive extracts from Graham Hunter's highly-anticipated new book, 'Barca: The Making of the Greatest Team in the World'. Last Friday's extract took a closer look at the most influential figure in the club's history: Johan Cruyff: Don't miss it!