Canberra United will take on Melbourne City in the W-League semi-final with kick-off scheduled for 2pm - around the hottest time of the day. Then the Central Coast Mariners host Adelaide United at 5pm in a battle of the A-League cellar dwellars. The FFA will wait until later in the week before considering their options, which could include going ahead as planned with drinks breaks during the games, delaying the start of one or both games or moving the W-League semi until after the Mariners game. Wilson Lo will be the doctor for both United and Central Coast and part of his job will be to decide whether drink breaks will be required. The decision on starting times lies with the FFA, with broadcaster Fox Sports also involved in discussions.

Lo said the heat would affect every player differently, with fatigue, dizziness, headaches, cramps and poor decision making among the milder symptoms, and loss of consciousness in extreme cases. The FFA's heat policy uses a wet bulb globe thermometer, which takes into account humidity as well as temperature, with a WBGT reading of 26-27.9 leading to drinks breaks and a reading of 28 or more leading to the game being delayed or postponed. Drinks breaks should also be taken if the standard temperature is above 31. ​Lo said the standard temperature was generally enough of a guide in Canberra and said the fact it was a double header complicated the decision-making process. "In Canberra you can just go on the dry heat - 32 you need to have some sort of break or extra water; 38 you shouldn't really be kicking off," he said.

"I think that applies to a lot of field sports in summer... It's not a good plan to have two games together." United coach Rae Dower backed the FFA's heat policy and said they'd never had any problems with it. They played in 36-degree heat at McKellar Park on Saturday, when Lo recommended there be two drinks breaks during each half. Dower said they weren't concerned if their kick-off time was changed and they had full faith in the medical staff and officials to come up with the right decision. "Everyone's just got to put player welfare and health first," she said.

"If the medical staff and all the officials suggest ... if it's above a certain temperature and we shouldn't be playing then we just wait. "You'd rather wait than put players in danger. If there is a decision to delay the kick-off until the conditions change then that's in the best interest of the athletes and the players and the game." The FFA said they would monitor forecasts throughout the week and keep in touch with the teams involved. On game day, they'll start taking readings at Canberra Stadium about five or six hours before kick-off and start to make decisions about start times. "The FFA monitors the forecast and temperatures for Sunday everyday leading up to the game and is in constant consultations with the clubs," a spokesman said.

"And once they do the reading with the wet bulb on match day the decision will be made then." W-LEAGUE SEMI-FINAL Sunday: Canberra United v Melbourne City at Canberra Stadium, 2pm. Loading A-LEAGUE ROUND 18

Sunday: Central Coast Mariners v Adelaide United at Canberra Stadium, 5pm. Tickets available from Ticketek.