Fijian cap Netani Talei returns from his heel injury for the Dragons' derby clash with Cardiff Blues at Rodney Parade on Boxing Day.
The fit again back row is one of the six changes that coaches have made to the Dragons starting line-up.
"These back to back games are so exciting," said head coach Darren Edwards.
"The whole place has come to life and it's been great for us from a commercial point of view and we will be looking to put on a big show."
Full-back Daniel Evans retains his place at number 15; he is joined in the back three by wingers Will Harries and Welsh international Hallam Amos. There is one change in the centre pairing with Ashley Smith stepping in at number 12 and Leach remains at 13.
Jason Tovey also keeps his place at fly-half and is joined by Wayne Evans as scrum-half, as Richie Rees is moved to the bench.
As Owen Evans remains at loosehead prop, there have been two changes to the front row with T. Rhys Thomas making his first start after coming back from injury and Nathan Buck comes in as tighthead prop.
The second-row remains the same as both skipper Andrew Coombs and Cory Hill impressed over in Galway last weekend. There is one change in the back- row as Netani Talei returns after his heel injury kept him out of the game last weekend, he starts as blindside flanker and Lewis Evans moves across to openside flanker and Welsh international Toby Faletau keeps his number eight jersey.
There have been seven changes made to the replacements bench with Sam Parry, Aaron Coundley, Francisco Chaparro, Rob Sidoli, Nic Cudd, Richie Rees and Ross Wardle. Steffan Jones remains at number 22 on the bench.
Meanwhile, centre Gavin Evans returns to the starting line-up for Cardiff Blues' make the short journey east.
Fit again midfielder Evans is one of six changes for Blues from the side that were narrowly beaten by Ospreys at the Arms Park last week.
The two other changes in the back division see Dan Fish take a spot on the wing while fly-half Rhys Patchell is back to partner Lloyd Williams at half back.
Lock Chris Dicomidis is named in the second-row, where he will partner Filo Paulo.
Macauley Cook moves into the back-row and takes the blindside flanker jersey while the final change for Blues is the recall of Josh Navidi at openside.
"We're all looking forward to a big finish to the year and the first of two derby games with the Dragons over Christmas and New Year," said Blues boss Phil Davies.
"The atmosphere will be white hot and it's not difficult to get the players up for these games because of the rivalry and history behind the sides.
"There was frustration in our dressing room after the Ospreys game and it is our job now to react in the right fashion and end 2013 on a high note.
"Dragons are a dangerous and talented outfit who will also be keen to bounce back after the defeat to Connacht to we need to be prepared for a really physical and intense game."
Form: Newport Gwent Dragons only victory in their last five Pro12 encounters was 23-8 at Glasgow Warriors in Round 8.
Dragons have won just one of their last nine fixtures with fellow Welsh Regions in the competition: 23-16 over the Scarlets at Rodney Parade on 20th September.
Cardiff Blues sole victory in their last five Pro12 matches was 17-13 at home to Benetton Treviso in round 7.
The Blues have not won away from home in the tournament since a visit to Edinburgh on 15th February, although they did draw 26-26 in Treviso on their last trip. Blues have won just three of their last sixteen clashes with fellow Welsh Regions since 2010 - all three were against the Dragons.
Of the last thirteen encounters between the two teams the Dragons have won just twice, both at Rodney Parade, in 2011 and 2012.
Dragons: 15 Daniel Evans, 14 Will Harries, 13 Pat Leach, 12 Ashley Smith, 11 Hallam Amos, 10 Jason Tovey, 9 Wayne Evans, 8 Toby Faletau, 7 Lewis Evans, 6 Netani Talei, 5 Cory Hill, 4 Andrew Coombs (c), 3 Nathan Buck, 2 T Rhys Thomas, 1 Owen Evans
Replacements: 16 Sam Parry, 17 Aaron Coundley, 18 Francisco Chaparro, 19 Rob Sidoli, 20 Nic Cudd, 21 Richie Rees, 22 Steffan Jones, 23 Ross Wardle
Cardiff Blues: 15 Leigh Halfpenny, 14 Alex Cuthbert, 13 Gavin Evans, 12 Dafydd Hewitt, 11 Dan Fish, 10 Rhys Patchell, 9 Lloyd Williams, 8 Robin Copeland, 7 Josh Navidi, 6 Macauley Cook, 5 Filo Paulo, 4 Chris Dicomidis, 3 B Bourrust, 2 Kristian Dacey, 1 Sam Hobbs (c)
Replacements: 16 Rhys Williams, 17 Thomas Davies, 18 Scott Andrews, 19 Ellis Jenkins, 20 Rory Watts-Jones, 21 Lewis Jones, 22 Gareth Davies, 23 Richard Smith
Date: Thursday 26th December
Venue: Rodney Parade
Kick-off: 1700 (local & GMT)
Referee: Ian Davies (Wal)
Assistant referees: Neil Hennessy, Jon Mason (both Wal)
TMO: Derek Bevan (Wal)