THE 'D' word - discipline - has been key for Donegal and their youthful boss Rory Gallagher as they face a crunch clash with an upbeat Roscommon in O'Donnell Park, Letterkenny on Sunday.

Last Sunday's bruising defeat to Kerry revealed a lack of discipline and some lapses in concentration in defence that resulted in considerable disappointment for the Fermanagh native.

Some quick thinking between Ciaran Donaghy and Peter Crowley set up Kerry for a crucial goal that was the clinching score for the Kingdom: "There were a few aspects of our play that were disappointing, even though the lads could not be faulted for effort," Gallagher said.

"We gave away too many frees and we definitely lost concentration for that Kerry goal, which was very quick thinking on the part of Ciaran Donaghy. That was disappointing because we had just go ourselves back into the match playing with the breeze.

"We had hoped to be pushing on, but instead it was Kerry who went on to win the match and we seemed to be switched off momentarily."

But Donegal will certainly need to be switched on for the visit of an ebullient Roscommon to O'Donnell Park on Sunday. Kevin McStay and Fergal O'Donnell's boys are now second in the table, thanks to fine wins over Kerry, Cork and Down.

And but for some inexperience against Monaghan, the Rossies would now be sharing the top spot with the unbeaten Dubs: "Our defeat last Sunday certainly puts Sunday's match into sharper focus and there should be a big crowd in Letterkenny to see what happens," Gallagher added.

"There is a lot at stake for both teams and Roscommon are on a very good run recently. They are a fit, young and big team, who can also play a fair bit of football and have a very good management team in Kevin McStay and Fergal O'Donnell.

"We will need to be at the top of our game as Roscommon have put in some really impressive displays. And those two wins over Kerry and Cork in particular will have given them a lot of confidence ahead of Sunday's match.

"They are an interesting mix of a clutch of talented and physically powerful young players and some mature talent in Senan Kilbride and Cathal Cregg. We are expecting a very big challenge on Sunday from Roscommon and last Sunday will hopefully sharpen our focus".

The last time Donegal met Roscommon in the NFL was a Division Two clash in Hyde Park that Tir Chonaill won. They later played in and lost the Division Two final to Louth under then team boss Brian McIvor.

Meanwhile, Roscommon star Sean McDermott knows a thing or two about some Donegal stars, like Paul Durcan, Eamon and Neil McGee, Karl Lacey, Barry Dunnion and Christy Toye.

McDermott was in Sligo IT along with that golden generation that took Sigerson titles in 2002, '04 and '05. These days, he is one of the elder statesmen of this impressive Roscommon outfit.

"Our main aim at the start of the year was to retain Division One status, with so many young players coming through from the U21 ranks," he said/.

"Division One is very important for us. When you come up from Division Two, people nearly expect you to go back down, but we feel that we have the capabilities of competing in this division, which we showed in the first game against Monaghan. And we have two very passionate football men in Kevin McStay and Fergal O'Donnell, which is a great help to us and we are just delighted to have them on board".

"I went to college with a lot of Donegal players in Sligo IT and this Donegal team is a very strong and very skillful team and we know that Sunday is going to be a very good test for us. We will need to be fully prepared. If you prepare well, your intensity levels are high and you execute your game plan then you will not be too far away.

Donegal should beware, as the Rossies are coming with a lot more than hope in their big hearts.