Sigurdsson hopes their trip to Europa League opponents Inter Milan will mark the start of another impressive sequence of results after an eight-match unbeaten run in all competitions also came to an end.
"It was disappointing but all we can do now is focus on the next game at Inter and make sure we go through," Sigurdsson said on tottenhamhotspur.com.
"We've been on an unbelievable run and sometimes things like this happen.
"We have to make sure we stay together, regroup and get ready for the next game.
"Hopefully we can go on another run between now and the end of the season."