Johnson hot on CharlieLee Johnson believes new-signing Charlie MacDonald will deliver the goals which will ensure Latics have a successful season.
Latics' manager was so impressed with the 32-year-old during a trial that he quickly snapped up the striker who has signed an initial 12-month deal.
Johnson, who has an option to extend it, said: "What has surprised me has been the quality of Charlie's finishing.
"I had him down as a workaholic and clever player, but I never thought of him as a clinical finisher.
"What I have seen of Charlie, I am sure he will score goals for us."
MacDonald, who got off the mark in last night's 2-2 draw against top Romanian side Dinamo Bucharest, has scored 125 career goals in 393 games, a record of almost one goal every three games.
Johnson continued: "I am delighted with the signing and Charlie will be an integral cog in our machine.
"He fits the profile in what we are looking for - he has experience, still has the legs to run and he can also score goals.
"Equally important he is a leaders and character and our young lads will learn from him.
"When I sat down with my coaching staff and discussed signing Charlie, they were unanimous in wanting him."
Johnson believes had MacDonald been 6ft 2in he would have played in the Premier League.
Latics' manager was also impressed by MacDonald's commitment to the club by leaving his family in London.
Johnson added that the signing of MacDonald may not be a massive one for the fans.
"I am sure everyone will learn to love him for what he does for the team. And I think he is a good signing for this level," he said.
MacDonald has considerable experience of League One and since 2008 he has played for Brentford, MK Dons and Leyton Orient.