Six Nations Championship:Ireland's preparations for tomorrow's RBS Six Nations encounter against Scotland have been hindered by injuries to Brian O'Driscoll and Girvan Dempsey which prevented the former from taking part, and the latter from completing, yesterday's squad session.

According to an official IRFU missive, O'Driscoll and Dempsey will undergo fitness tests today before their participation is confirmed, with the demoted Geordan Murphy returning from Leicester yesterday.

While the rest of the squad trained in UCD yesterday, the union statement said that O'Driscoll, whose calf seized up in Tuesday's training, "completed a fitness session and had no reaction to his calf afterwards. He will undergo a full fitness test tomorrow to confirm his availability for the weekend."

It was also confirmed Dempsey "picked up a knock to his left hip during the training session today and being so close to the game, Geordan Murphy, who was named in the Leicester squad this weekend, has been called back into the Ireland camp as a precaution. Dempsey will undergo a fitness test tomorrow to determine if he will play on Saturday."

However, the word emanating from the camp is that while O'Driscoll is still confident of playing, Dempsey's injury is worse than is being publicly conveyed.

The 80-times capped full-back has been the regular first-choice starting fullback since the start of last season's Six Nations save for being rested in Argentina last summer and the Scottish warm-up match in Murrayfield, and when injured for the final World Cup pool game against Argentina.

Were the captain to be ruled out, the expectation is that Shane Horgan would be promoted to the midfield, with Luke Fitzgerald filling his place on the bench, although it is understood that Tommy Bowe was tried out there yesterday with Horgan on the wing.

Murphy, literally, mustn't know whether he's coming or going. Dropped from the right wing to make way for Bowe's recall on Tuesday and also left out of the 22, he returned to Leicester that day suffering from the knee injury which prevented him from training on Monday before being summoned yesterday to provide cover at fullback. Thus, he will not have trained with the team this week either.

The Scots, for one, will not be inclined to pay much heed to any official line given the memory of the Friday before this fixture in Murrayfield three seasons ago, when the Irish camp maintained the line that O'Driscoll and Gordon D'Arcy were still in a race against time to recover from hamstring injuries suffered the week before in Rome.

It later transpired that both were already en flight to the ice chambers of Spala in Poland.

The union statement confirmed that replacement prop Tony Buckley, who had been sidelined earlier in the week with a badly bruised finger, "came through the session and also a full fitness test and has been confirmed as being fit to take his position among the replacements for the game."

Cork Con and Munster prop Darragh Hurley had been called in as cover.