Michael Bent will win his 100th Leinster cap when the province face Edinburgh at Myreside on Friday night in the Pro14 (7.35pm).
Bent made his debut in a 37-7 home win over Zebre at the RDS back in 2012.
"One of the qualities that Michael has - he's a quiet character - but he goes to work," said scrum coach John Fogarty this week.
"He has worked on his game, he's worked on his scrum, and he's improved hugely. He's very important for us.
"We've seen him over the years play both sides of the scrum, so he's shown himself to be versatile. He's improved his game, and he's adapted to different coaches that have come in.
"Credit to Michael. I'm delighted for him and his family that he's reached 100 caps."
Bent will start at tighthead prop on Friday, with Peter Dooley loosehead. Richardt Strauss completes the front row and is named captain.
Will Connors will make his senior debut, starting at openside flanker. He is joined by Josh Murphy and Max Deegan, to complete a youthful back-row trio.
The second-row pairing of Ross Molony and Scott Fardy completes the pack. Rory O'Loughlin, at outside centre, and Noel Reid, at inside centre, form the visitors' midfield.
Ross Byrne and Jamison Gibson-Park will make up the half-back pairing. Dave Kearney is at full-back for the first time since February 2015, with Barry Daly on the left wing.
Fergus McFadden and Luke McGrath have both been released from Ireland camp for the Edinburgh match. McFadden will start on the right wing and McGrath has been named among the replacements.
Adam Byrne, named among the replacements, could make his return from injury. Byrne last featured for Leinster in the Pro14 defeat away to Glasgow Warriors in November.
Leinster (v Edinburgh): D Kearney, Fergus McFadden, Rory O'Loughlin, Noel Reid, Barry Daly, Ross Byrne,, Jamison Gibson-Park; P Dooley, R Strauss (capt), M Bent, R Molony, S Fardy, J Murphy, W Connors, M Deegan
Replacements: B Byrne, E Byrne, O Heffernan, Mick Kearney, P Timmins, L McGrath, C Frawley, A Byrne
Eperienced lock Andrew Browne (above) returns to Kieran Keane’s Connacht line-up for the Pro14 clash with the Ospreys at the Sportsground on Friday night (7.35pm).
Also back from injury and in the starting XV are lock James Cannon and out-half Craig Ronaldson.
With Bundee Aki away on international duty, Tom Farrell and Eoin Griffin form the centre pairing. Likewise, with Kieran Marmion’s absence, Caolin Blade starts at scrum half.
Having recently announced that he will retire at the end of this season, John Muldoon will captain the side from his number 8 position. He will be joined in the back row by Eoghan Masterson at blindside and openside Naulia Dawai.
The back three is made up of Tiernan O’Halloran at full back, with Cian Kelleher and Matt Healy on the two wings.
"We are up for this game, we know the importance of it," said Keane.
"This is a really important block of games for us and will have a big bearing on our Pro14 season. We have a quarter-final in the Challenge Cup to look forward to later in the season but there is a lot of rugby to play before that."
Connacht (v Ospreys): T O’Halloran, C Kelleher, E Griffin, T Farrell, M Healy, C Ronaldson, C Blade; D Coulson, T McCartney, C Carey, A Browne, J Cannon, E Masterson, N Dawai, J Muldoon (Capt).
Replacements: S Delahunt, P McCabe, D Robertson McCoy, G Thornbury, J Connolly, J Mitchell, J Carty, PiAhki.
Alan O'Connor (above) will captain Ulster for the first time in the historic Pro14 visit of Southern Kings to Kingspan Stadium on Friday night (7.35pm).
Flyhalf Johnny McPhillips, who has made four appearances as a replacement, will make his first senior start in head coach Jono Gibbes' opening game in charge.
Also in the backline, Luke Marshall and Craig Gilroy return from injury lay-offs to earn starting berths at outside centre and right wing respectively.
McPhillips will have experience either side of him in the form of scrumhalf John Cooney and inside centre Stuart McCloskey, while Rob Lyttle and Charles Piutau will join Gilroy in a potent back three combination.
Gibbes has opted for Andy Warwick, John Andrew and Wiehahn Herbst in the front row, with Kieran Treadwell partnering O'Connor at lock. The loose forwards are Matthew Rea, Sean Reidy and Nick Timoney.
Hooker Rob Herring has been released from the Ireland national camp and will provide cover on the bench, while Ireland U20 duo Matthew Dalton and Jonny Stewart are also included among the replacements.
Kyle McCall, Rodney Ah You and Chris Henry are the other forwards included in the match day squad, with Darren Cave and Louis Ludik providing further backline options.
Ulster (v Southern Kings): C Piutau; C Gilroy, L Marshall, S McCloskey, R Lyttle; J McPhillips, J Cooney;
A Warwick, J Andrew, W Herbst, A O'Connor (captain), K Treadwell, M Rea, S Reidy, N Timoney;
Replacements: R Herring, K McCall, R Ah You, M Dalton, C Henry, J Stewart, D Cave, L Ludik.