Leicester outside-half Tom Hardwick kicked a penalty to seal a last-gasp Challenge Cup win against Cardiff Blues.
Hardwick slotted over his third penalty, with number eight Jordan Coghlan also scoring a try.
Blues had led through an Aled Summerhill try and two Jarrod Evans penalties.
New Wales squad centre Willis Halaholo is a doubt to play the Barbarians after limping off with a knee injury.
Blues coach John Mulvihill will be disappointed his side could not defeat a gritty second-string Leicester side who have struggled in the Premiership this season
Mulvihill made nine personnel changes from the 38-16 win at Calvisano.
Wales internationals Hallam Amos and Owen Lane both returned from the World Cup, but prop Dillon Lewis, scrum-half Tomos Williams and wing Josh Adams are yet to feature.
Amos made his Blues debut after eight years at the Dragons and produced an impressive display.
New Zealand-born centre Halaholo and flanker Shane Lewis-Hughes were among the newcomers named in the Wales squad to face the Barbarians on Saturday 30 November.
World Cup prop Ellis Genge made his first Leicester start of the season after coming off the bench in the 41-20 win over Pau, but Ben Youngs, Dan Cole, Manu Tuilagi and George Ford were still missing.
Joe Thomas made his Tigers European debut at centre as Leicester made 13 changes.
Fly-half Evans was one of six Wales squad members on show and opened the scoring in the fifth minute following a deliberate knock-on.
Halaholo then demonstrated the sidestepping feet that have seen him included in Wayne Pivac's first Wales squad to set up the situation for Evans to double the lead.
Halaholo then limped off as Leicester responded with a try for number eight Coghlan following fine build-up work from flanker Guy Thompson and captain Ben White.
Evans moved to centre with replacement fly-half Jason Tovey making an immediate impression with a clever cross kick to set up a try for Blues wing Summerhill.
Hardwick added two penalties either side of half-time to level the scores. The match erupted after 68 minutes in a scuffle between the two sides before Evans missed a touchline penalty.
Summerhill was denied a second try after his foot was just in touch before scoring following a cover tackle from Leicester replacement Sam Costello.
Leicester took advantage as Blues were penalised for not releasing and Hardwick sealed victory with the final kick of the game.
Leicester Tigers head coach Geordan Murphy told S4C: "We thought we were in the game at half time. We were a little bit naïve at the back end of the first half.
"We obviously knew we were going to be up against it - we're only a young bunch. We didn't want to give Cardiff anything too cheap - we wanted them to earn everything in the second half.
"We worked very hard for each other and we got away with a couple of really big moments but thankfully on the night it went our way."
Cardiff Blues head coach John Mulvihill said: "I thought we played some good rugby but lacked a bit of control in some of the finer points.
"We did not play in the right areas towards the end and we turned over the ball 19 times. We won most facets of the game but not on the scoreboard in the end and it was our own fault."
Blues: Amos; Lane, Lee-Lo, Halaholo, Summerhill; Evans, L Williams; Domachowski, Belcher, Andrews, Davies, Turnbull, Lewis-Hughes, Boyde, N Williams,
Replacements: Myhill, Thyer, Assiratti, Cook, Botham, Jones, Tovey, Morgan.
Leicester: Worth; Thompstone, Thomas, Viljoen, Forsyth, Hardwick, White (capt), Genge, Kerr, Heyes, Lavanini, Wells, Lewis, Thompson, Coghlan
Replacements: Clare, Gigena, Leatigaga, Jordan, Smith, Simmons, Costelow, Steward
Referee: Pierre Brousset (France)
Assistant referees: Tual Trainini (France), Laurent Cardona (France)
TMO: Eric Briquet-Campin (France).