"Everyone will get a start in the first three matches. Selection for the side to play the Barbarians was quite easy as we've gone mainly with the players who have been training with us over the last two weeks," said Gatland.
"Owen Farrell has been going well and he has fitted in well and there is a huge amount of competition within the squad. Everyone feels that if they play well, they will get selected and the players on Saturday have the chance to put pressure on the players for the next week.
"Sam has had a sore knee for the past 10 days and he has had a steroid injection to ease the swelling. He has been told to stay off it for five days.
"He really wanted to play this weekend, but it isn't worth the risk. We don't want him to play for three or four weeks and then find him having a problem later on..
"The other players carrying slight injuries are Sean O'Brien, who has bruising on the bone, Rob Kearney, whose tight hamstring forced him to pull out of the RaboDirect PRO12 final, and Gethin Jenkins, who has a slight calf strain. They will all be fit for the games against the Force or Reds."
Gatland was spoilt for choice when he went looking for the right man to take over the captaincy at the Kong Kong Stadium this weekend having not only O'Connell, but also Brian O'Driscoll, the 2005 skipper, in his squad.
In the end he went for O'Connell, who wasn't involved in a domestic final like O'Driscoll last weekend, and he will be one of six former Lions in the matchday 23 on Saturday.
"It was a pretty easy decision to make on the captaincy. Paul O'Connell has been great in the squad in the last few weeks and has given us some good leadership," said Gatland.
"Given his experience, and the respect he has in the squad, it was the obvious thing to give him the captaincy. With the heat and weather conditions most of the players will come off the bench and we want to give them a start and a taste of things."
The heat and humidity here in Hong Kong - Saturday is predicted to be one of the hottest days of the year so far - is bound to make it difficult for players on both sides, but Gatland intends to send out his side with every intention of playing attractive rugby.
"We have already stated we want to go out and play rugby on this tour. We want to move the ball and score lots of tries," he added.
"We have a southern hemisphere referee in charge of the game and it's important that we send a message to the southern hemisphere referees that we want to be a positive side and move the ball.
"We will be pragmatic and adapt to conditions and styles but, in the end, I don't care about the style as long as we win."