Jose Mourinho expects Manchester United will soon sign Arsenal's Alexis Sanchez after he missed the Gunners' win over Crystal Palace to travel north to discuss the switch.
Sanchez was left out of Arsenal manager Arsene Wenger's squad as he nears a move to Old Trafford that could see Henrikh Mkhitaryan move in the opposite direction.
Like Sanchez, Mkhitaryan was missing for United's fixture at Burnley while negotiations continue.
Speaking after United's 1-0 win over Burnley, Mourinho said of signing Sanchez: "I expect soon or never. I think it's so close, so close - so close that if it doesn't happen (soon) it's not going to happen.
"So I am positive, I know that my people are doing everything, absolutely everything they can - the owners with the green light, Mr (Ed) Woodward's working hard.
"I think everybody is giving everything they can and I think they are going to be successful."
Sanchez had trained with Arsenal's first team as usual on Friday and Wenger had said he could be involved against Palace should a move to United not be completed beforehand.
However, Wenger confirmed after the game that the 29-year-old was omitted with negotiations ongoing.
"I didn't take him because there is a question of him moving to Manchester United and you cannot drive up north and as well play football," Wenger said.
"That's difficult so that's why I decided to leave him out.
"I expect it to happen maybe, but I cannot announce it because in the next 48 hours it will be decided one way or the other.
"In these kind of things, as long as it's not over the line you cannot say it will happen because the negotiations become more and more longer and edgy because every detail becomes important nowadays.
"If you want to have a bet, it could happen."
Mourinho confirmed that both Ed Woodward, the club's executive vice-chairman, and Matt Judge, their head of corporate finance, were working on a Sanchez deal that will give the United manager another attacking option.
Winger Anthony Martial scored the winner against Burnley but Mourinho feels he needs greater options going forward.
"In this moment there is no competition for places, we have four attacking players for three positions, three are starting, one is on the bench," he said.
"You look to the attacking areas and we need that extra competitive internal competition but more solutions for us so let's see."
One of his attacking options, Mkhitaryan, missed a second successive match due to the uncertainty regarding his own future.
Mourinho had already revealed on Friday that he would not consider the 28-year-old Armenian at Turf Moor while discussions continued over the potential deal involving Sanchez.
Asked about a swap deal, Arsenal boss Wenger said: "It happens only one way, if the other way happens as well.
"That's why it takes longer as well because it has to be co-ordinated."