Johan Ackermann believes Gloucester face some "very tough challenges" after two late Billy Twelvetrees penalties earned a 20-16 Aviva Premiership win over Sale.

A strong second-half performance from the Cherry and Whites pack earned them a deserved victory in front of a sell-out crowd at Kingsholm.

The triumph avenged Gloucester's 57-10 thrashing at the AJ Bell Stadium in September, but had looked in doubt when the lethargic hosts trailed 9-7 at half-time.

AJ MacGinty scored all Sale's points with a try, conversion and three penalties, but tries from David Halaifonua and Ben Vellacott and 10 points from the boot of Twelvetrees edged Gloucester over the line.

Ackermann said: "We never got going as we got over excited and needed to calm it down but I'm grateful we got over the winning line.

"We want to play exciting rugby but we needed to look after the ball better.

"Our error-count was high and our discipline poor but the guys stuck at it and we secured vital turnovers and scrum penalties at crucial times.

"We are growing as a team together but it's frustrating as the errors are not at the level we want.

Next up for Gloucester is a trip to Northampton and Ackermann added: "They'll have their backs to the wall so they will be dangerous and all sides playing at home will cause a threat.

"It's nice to end the year with a win and in fourth place in the table but there are still four or five months to go with some very tough challenges ahead."

Sale scrum-half Faf De Klerk made the try for MacGinty and director of rugby Steve Diamond felt he was the best player on the pitch.

He said: "Despite us losing, Faf was man of the match as he brings what people want to see.

"It was always going to be tight and the first half went very well but we didn't take our chances.

"We gave away silly penalties and the pitch was heavy. We are not used to playing on a surface like that and it sapped our energy levels.

"I was disappointed with parts of our play but they had a big pack of forwards who were backed by a large crowd and they controlled the game better.

"I would have liked the four points but we've still got six points from our last two games so we'll have to dust ourselves down and go again against Harlequins next week."