London - Star flyhalf Jonathan Sexton was included in the Ireland squad for the first two rounds of the Six Nations announced on Monday despite a recent injury scare.
Sexton has been dealing with a calf complaint but that did not stop him being selected in a 40-man squad for Ireland's tournament opener against Scotland at Murrayfield on February 4 and their February 11 match in Rome against an Italy side coached by former Ireland international Conor O'Shea.
British and Irish Lion stand-off Sexton hobbled off during Leinster's 24-24 draw at French side Castres on Friday, but Ireland officials hope his withdrawal was merely a precaution rather than anything more serious.
Uncapped brothers Niall and Rory Scannell were also both selected by Ireland coach Joe Schmidt.
Niall will contest the reserve hooker position behind Ireland captain Rory Best with Leinster's James Tracy while Rory Scannell is a centre.
Ireland will be without Sean Cronin, Best's regular deputy, through injury.
Andrew Conway, a wing and fullback, is the third uncapped player in the squad.
"It has been good to watch the players over the past two months and great to see many of them doing so well," said Schmidt.
"As always there were some difficult decisions but we feel that the group is a good mix with a number of key players having good experience and a number of newer players having gained valuable experience and confidence during the summer tour to South Africa and the recent autumn series," the New Zealander added.
Last year saw Ireland beat the southern hemisphere 'big three' of South Africa, New Zealand and Australia.
In particular a stunning 40-29 win over world champions New Zealand in Chicago in November - their first victory against the All Blacks - led many pundits to proclaim Ireland as the main challengers to Grand Slam title-holders England in this season's Six Nations.
Ireland will face England in the final round of the Championship in Dublin on March 18.
Ireland 40-man squad announced on Monday for their opening two matches of the 2017 Six Nations Championship against Scotland at Murrayfield on February 4 and Italy in Rome on February 11:
Tommy Bowe (Ulster), Andrew Conway (Munster), Keith Earls (Munster), Craig Gilroy (Ulster), Robbie Henshaw (Leinster), Paddy Jackson (Ulster), Rob Kearney (Leinster), Kieran Marmion (Connacht), Luke Marshall (Ulster), Stuart McCloskey (Ulster), Luke McGrath (Leinster), Conor Murray (Munster), Tiernan O'Halloran (Connacht), Garry Ringrose (Leinster), Rory Scannell (Munster), Jonathan Sexton (Leinster), Andrew Trimble (Ulster), Simon Zebo (Munster)
Finlay Bealham (Connacht), Rory Best (Ulster, capt), Jack Conan (Leinster), Ultan Dillane (Connacht), Tadhg Furlong (Leinster), Cian Healy (Leinster), Jamie Heaslip (Leinster), Iain Henderson (Ulster), Billy Holland (Munster), Dave Kilcoyne (Munster), Dan Leavy (Leinster), Jack McGrath (Leinster), Sean O'Brien (Leinster), Tommy O'Donnell (Munster), Peter O'Mahony (Munster), Donnacha Ryan (Munster), John Ryan (Munster), Niall Scannell (Munster), CJ Stander (Munster), Devin Toner (Leinster), James Tracy (Leinster), Josh van der Flier (Leinster)