Celtic manager Brendan Rodgers says his side needs to raise its level of performance if they are to retain the Scottish Cup.
James Forrest's first hat-trick secured a 3-2 win over Partick Thistle to send Celtic into the quarter-finals.
Rodgers, though, says his team needs to improve as they bid to defend the trophy.
"If we're to win the cup we need to play better and make less mistakes at the back," Rodgers said.
"It should have been less nervy. We started the game very well, good structure to our team, good positioning and ended up getting two goals.
"Big mistake that we make that gives them oxygen in the game. That gave them the lift and our rhythm was bitty for the rest of the half.
"With five minutes to go, it's tight, and there's a brilliant bit of defending from Kieran Tierney at the back post to prevent them making the opportunity. Overall a good win for us, but we made it really difficult.
"We were good going forward but behind we need to be better with and without the ball."
A minute's silence was held before kick-off in tribute to former Celtic midfielder Liam Miller, who died at 36 after suffering from cancer.
Forrest scored twice in the opening 10 minutes, and only a diving save from Tomas Cerny prevented him completing his hat-trick in the opening quarter.
A Jozo Simunovic mistake gifted Kris Doolan a chance, and the Partick Thistle striker lobbed Dorus de Vries to score his 112th goal in his 350th appearance for the club.
Forrest completed his treble eight minutes into the second half, although Conor Sammon scored a consolation goal for Partick Thistle in the closing stages.
"James Forrest was outstanding, the player of real quality on the pitch, how he received the ball, how he pressed the game and his goals were brilliant," said Rodgers.
"He's one of the best receivers of the ball I've ever worked with, whether it's in a tight space or in the middle of the pitch. He's getting real confidence in his game.
"He's got an incredible ability with the ball, how he runs with it, and a nice little body swerve and he's got a finish now and is getting into areas to get goals. All three goals were brilliant."
Partick Thistle manager Alan Archibald was happy with the resilience shown by his side, but not the sloppiness in the opening period that saw them fall two goals behind.
"We gave ourselves a chance towards the end, but we can't start a game in that manner," Archibald said.
"The first 15 minutes we were all over the place, but once we regrouped and got a grip on our shape and formation, we always looked a threat.
"We got ourselves back in the game and credit to the lads for the character they showed. On another day, we could have got a replay."