Neil Harris has described Millwall's recent business in the transfer market as a "signal of intent" ahead of the club's return to the Sky Bet Championship.
The Lions secured the services of Wolverhampton midfielders George Saville and Jed Wallace earlier this week - their third and fourth signings of the summer.
"Those two players have been here before on loan," Harris said. "They've both performed really well in Millwall shirts, which is key for me.
"We have invested in them at their age so they can grow with us. They are only going to get better as footballers and I do think that our recent signings are a signal of our intent to be competitive in the Championship.
"We are a club that is on the up and we want to build on the momentum from last year. George and Jed are a good fit for us this summer."
And while the Lions boss is pleased with how business is progressing, Harris hopes to lure at least another two new players to the club ahead of the 2017/18 campaign.
"I still feel we are a couple players short in certain areas," the manager added. "Will we sign them this week or next week? Maybe not. We will have to be patient.
"At times last year we had difficult spells. If we have difficult spells in the future I want to have the option to shake it up and pick a different team or formation to make us better."