Jose Mourinho says waiting for Romelu Lukaku to end his goal drought for Manchester United is like getting ketchup out of a bottle.
The Belgian striker last found the net in a 2-1 win over Watford in September - his fourth of the season - and his run of eight games without a goal has coincided with a difficult spell for United.
But the Red Devils boss is not worried about Lukaku's form, citing the words of former United star Cristiano Ronaldo as the reason to keep faith in the attacker.
"I think one of the best scorers in football had funny words about it," he told Sky Sports. "It was when Cristiano Ronaldo was speaking about the ketchup bottle and when you [shake it]. The goals are coming and coming and coming.
"I believe with Lukaku that this will happen, but the reality is that in this moment it's not happening.
"There's been lots of matches in which he's not scored a goal, and not just scoring but also the performances, the happiness in the performances, I think is the problem.
"But he's a good player, a good boy, and I think the best way to do it is to just keep working and the moment will arrive."
United welcome Everton to Old Trafford on Sunday looking to move up from 10th place in the Premier League.
With the Toffees sitting a point ahead and on a three-game winning streak in the top flight, Mourinho feels there is not much between the two sides.
"Everton have one advantage in relation to us, which is a similar potential, but much less expectations," he added. "Everything they do nicely is positive, the mood has been calm during their investments.
"They've improved their team, they've had time to work, no pressure at all, and the potential is very similar.
"We have on us that extra factor that we are Manchester United, but we have to be strong enough and brave enough to know that it's a game that we can win."