Massimo Carrera spoke of how his Juventus side made life difficult for themselves during their 2-1 win over Siena at the Stadio Artemio Franchi on Sunday.
The 48-year-old felt like the Bianconeri could have wrapped up the points early on but they had to wait until the 85th minute for Claudio Marchisio to score the winner for them.
The win means Juve stretch their unbeaten run to 46 league games whilst continuing to set the pace at the top of Serie A but Carrera insists the result could have been a lot more comfortable had the Old Lady taken their chances.
"Surely this game could have been won much earlier. We lacked a little ruthlessness, and for this we had to suffer until the end," Carrera told reporters after the match.
"It is obvious that in some matches we may lack a clinical edge, but you cannot always win by four or five goals."
The Juventus boss also denied claims that Giorgio Chiellini should have been sent off after the defender lunged in on Felipe when he had already been booked.
He added: "The first did not seem like a foul worthy of a yellow card. The second, he was looking to win the ball and even that wasn't so bad."