The full-back – who celebrated his 21st birthday yesterday – has been battling with Mikael Lustig, Charlie Mulgrew and Emilio Izaguirre for the full-back positions this season.
Now left-sided defender Rami Gershon has joined the fight after being brought in on a six-month loan.
Lennon is intent on adding even more players to his squad – with Nigerian left-back Juwon Oshinawi confirmed as one target – before the window closes in just over two weeks.
But with a domestic Treble and a Champions League glamour tie in Celtic's sights, Matthews is all in favour of this recruitment drive.
He said: "The competition for places is going to be stiffer, and that can only help us.
"You know if you're not playing well you'll be out of the team.
"This should help make sure everyone's 100% focused on what they need to do."
In the second half of the season, Celtic's task will be to successfully finish the job they started before the break.
"I don't think anyone gave us much chance of getting through our Champions League group and we've done that," he said.
"We'll go into the Juventus game fully confident we can get to the last eight.
"In the other competitions, we just need to be focused and try to win them all.
"The Treble is a really tough thing to do. If we manage that it would be a great achievement.
"We're confident we can do it and that's our goal.
"I think the squad size will help. We've added a few new faces and with the players we've got, we can do as well as we want to do."
The Welshman already has a championship and a Scottish Cup winner's medal in his collection, and, with youth on his side, can expect to have the opportunity to swell this collection.
"People perhaps don't realise how young I am," he said.
"I made my debut for Cardiff when I was 17, so have been playing for three or four years now.
"It's going well with Celtic at the moment. I feel I'm playing not bad myself. Before I got the knock on my ankle was my best form of the season.
"I just need to get back into it now and, hopefully, get my place back in the team."
Matthews is benefiting from the experience of Danny McGrain, now one of Lennon's first-team coaches, and said: "He's a Celtic legend.
"Having him around is brilliant, not just for me, but for the whole squad.
"I don't mind playing left-back and, when I do play there, he tells me what to do and what not to do.
"My best performance at left-back probably came against Barcelona. It was probably the team's best performance, too.
"I don't really mind when I'm asked to play over there. I feel comfortable left or right.
"Good players have got to do what their manager asks of them."