Trent Alexander-Arnold, Diogo Jota, Alisson and Stefan Bajcetic are all close to full fitness with Liverpool also in the thick of the Premier League title race.
"Obviously, we didn't rush it with them," Klopp told reporters. "Trent and Jota have been training together a lot for a couple of weeks. They did a lot of training but they were doing very well yesterday.
"We will see how they go but they are back in training and we have to see how we use them. Yes, we need them back but we need them in the best possible shape and we need them in rhythm."
Liverpool, who won the League Cup this season, are level with Arsenal on 71 points atop the Premier League table although trail on goal difference. They squandered a chance to claim top spot outright with a 2-2 draw at Manchester United on Sunday.
"Very disappointed after the game but it was quickly forgotten about," midfielder Harvey Elliott said. "The good thing about football is we've got another game to focus on."
The Liverpool players would love to win the Europa League for Klopp in his last season with the club.
"With the gaffer leaving at the end of the season, winning it would be the best possible way for that to end," Elliott said. "We as players will be doing everything we can for that to happen and we want to give everything back to him.
"He's been so influential in all our careers."
Liverpool travel to Atalanta, who are sixth in Italy's Serie A, on April 18 after hosting Crystal Palace in the league on Sunday.
Klopp expects Atalanta, managed by long-serving boss Gian Piero Gasperini, to pose Liverpool problems.
"There are now only great teams left in the competition," Klopp said.
"It's really outstanding and we know what Atalanta are all about. Gasperini is doing an incredible job there for years and years and it's difficult to play against Italian teams, always was.
"Tactically they're super disciplined and super dangerous in a lot of areas, so we have to be at our best to get into the next round over these two legs."
The German was also keen to stress that planning for so many games was not a problem.
"We didn't really have this last year because we were knocked out of Europe pretty quickly but other than that, it's a pretty standard situation for us," he said. "It's not much about training, it's about meetings and analysis and that kind of thing."
