Messi and De Jong are both available for the game as the Catalan giants look to keep the pressure on leaders Atletico Madrid, who are four points better off ahead of Sunday's trip to Sevilla.
However, both players risk being banned for next Saturday's showdown with bitter rivals Real Madrid, having each been booked four times already this season.
💪 Everyone is back!— FC Barcelona (@FCBarcelona) April 4, 2021
🔊 𝐒𝐨𝐮𝐧𝐝 𝐎𝐧 🔊 pic.twitter.com/h9TauYjXmJ
But while the pair may be walking a disciplinary tightrope, Koeman is ready to risk star man Messi and central midfielder De Jong against Valladolid.
"We know that these two players are one card away, but it is not the time to rest players due to cards or freshness," he said at Sunday's pre-match news conference.
"We have ten games left. There is always the risk, but the best thing is to put the team out that I think can win the game."
Messi has been directly involved in 23 league goals in 2021 - 16 goals and seven assists - which is more than any other player in the top five European leagues.
The Argentinian has had a direct hand in eight goals in his last four LaLiga games against Real Valladolid - four goals and four assists.
Those goal involvements have helped Barca to 13 wins in their previous 14 LaLiga games against Valladolid, with the only exception being a 1-0 defeat away from home in March 2014.
Sergio Gonzalez's side have won just one of their past 11 league games, but Koeman will not take Monday's opponents lightly.
"You have to be prepared, you can't think that it will be an easy game," he said. "We have to go in with a lot of energy and rhythm and be good with the ball.
"We have to get back to our level. It could be a game without problems, but you always have to work hard to win."
Gerard Pique returned to training this week after recovering from a knee problem, while Sergi Roberto is also closing in on a comeback after two months on the sidelines.
Koeman will make a late decision on whether the defensive duo are ready to play a part against Valladolid.
"They are training with the team lately. They have improved a lot," he said.
"These are decisions that will be made tomorrow after the last training session. We aren't going to take risks [with injuries], nor next week, because there are more games coming this season."