Sunday's top-of-the-table clash saw the Reds keep the runaway leader at bay for just over an hour before Costa Rican Jean Carlos Solorzano stole the only goal of the game to seal the 1-0 win, but for Coolen, injuries to key players proved to be more disappointing than the defeat.

Keenan was stretchered off in injury time as the Reds finished the match with 10 men, with confirmation the midfielder suffered a broken leg.

"Joey Keenan is definitely out, he's broken his fibula so he's out for the whole season," he said. "To be honest at the end of the day I was more disappointed about that than the loss.

"I was happy with the performance from my team in the last two games they played. If you lose the game, you're still happy with the performance of your players.

"If you lose the game it's not positive but maybe losing a couple of players I have more problems with that."

While Keenan is the only definite casualty, Boogaard, Flores and Cassio will all undergo MRI scans to reveal the extent of their injury concerns.

Immediately after the defeat, Coolen acknowledged the Reds excessive scheduling of five games in 17 days had left United fatigued and susceptible to soft tissue or muscular injuries.

The Dutchman admitted there were concerns over some of his players at half time but the gruelling schedule left Coolen with few options as most of the squad were no longer fit or fresh.

"Playing games like we have, five games in 17 days and a lot of away games that causes you some problems," he said.

"It wasn't the reason that we lost the game, definitely not, but it could be the reason that we lost some players.

"There will be a lot of MRI scans today and we'll have to find out during the week if we can fit them in the squad for the next game.

"Boogaard will have an MRI today. He was having trouble with his groin but there was a little bit better feeling than there was yesterday so that could be positive.

"And it's the same with Flores and Cassio. They both have problems on their hamstring. It's all about what I said yesterday, the schedule we have.

"There were already problems at half time and we played a real good 45 minutes I think. What I saw at half time was definitely the reason of the schedule of the last couple of weeks but we couldn't change it."

There is some positive news for the Reds though, with new signings Uruguayan Francisco Usúcar and Dutchman Andy Slory certain to feature against the Victory after failing to receive their International Transfer Clearance in time for the Roar match.

Coolen admitted the pair will need more sessions with the group after being restricted to mainly individual training due to the Reds demanding festive season.

"Until now they've only had a lot of individual training sessions because we have always been playing and travelling and recovery sessions," he said.

"We have at least one week to prepare them for the game against Melbourne Victory (on Sunday). They are in the squad and we'll find out if we can start them on the bench."

United's third international signing, Costa Rican Diego Estrada is still not a done deal but Coolen hopes to unveil the skilful No. 10 by week's end.

He added: "Diego Estrada is still not 100 percent because he's still not here. We are talking with him of course and it could be something for a couple of days or weeks later."

Now Coolen wants to see clubs be allowed larger squadss to cope with the punishing schedule of matches.

"Every club has had the problem at some time so it isn't fair to say only we've had it," Coolen said.

"I think it is something to think about. We don't have big squads like in Europe, 30-35 players. They'll play a midweek fixture once every two weeks not two or three in a row, they have bigger squads so they can rotate players.

"It's all about the fitness of our team at the moment and it's all because of the schedule. We have a few players who are not fresh and fit anymore, we're definitely not fresh anymore.

"There were almost not enough training sessions, there were just recovery sessions between games."

He added: "I don't blame anyone for it, but it's definitely to do with the freshness of the players and the schedule of the last few weeks.

"Every team has the same problem. The players are professionals and they train hard so we don't have to feel sorry for them but you need time to recover."