The Cowboys host the Knights on Saturday afternoon, with the Maroons teammates set for a one-on-one battle to savour.
Holmes was outstanding in the 43-18 win over the Dolphins in round one, while veteran Gagai impressed Holmes in the 28-12 loss to Canberra.
Valentine Holmes (left) watches Dane Gagai during a Queensland State of Origin training session. (Dave Hunt/AAP PHOTOS)
"I watched their game last week and I know they didn't win but he was a big part of their team," Holmes said.
"He had 20-plus carries and defensively he was strong. He just runs hard, tackles hard and wants to do well for his team no matter what jersey he is in.
"It is going to be one challenge for me to take on, but it should be good if we play like we did last weekend."
Holmes' combination with his left winger Murray Taulagi is one of the side's great strengths, and the duo linked up for a try and looked dangerous against the Dolphins.
The Knights will need to be at their best to stop the powerhouse pair.
"I love playing inside Murray," Holmes said.
Murray Taulagi and Valentine Holmes have formed a powerhouse pairing at the Cowboys. (Jono Searle/AAP PHOTOS)
"He has always been there to have my back if I have made a misread or if the opposition has got a pass away. He is always there to clean it up and make a good tackle or intercept.
"He did a couple of those on the weekend, and it brings him into the game and gives him confidence."
Holmes said the addition of new assistant coaches Justin Morgan and James Maloney had brought new ideas to the squad after the Cowboys missed the finals in 2023.
"We didn't make the finals last year, so everyone came back to training earlier and we ripped in from the start," he said.
"We have got two new coaches and are learning a new system with defence and what Jimmy does in attack.
"It is always exciting to learn again, and everyone has bought in."
Cowboys players have spoken this week of the impact made by Maloney to the side's attack.
Centre Zac Laybutt said Maloney had encouraged him to play what is in front of him when an opportunity arises.
Fullback Scott Drinkwater explained how Maloney had challenged the entire squad.
"He is hard to please, Jimmy, which is good," Drinkwater said.
"There is always something to improve on. He has helped by changing a few things and making more blokes accountable - not just the halves and fullback about seeing stuff on the field - so everyone is looking up and talking."
