Mount made his debut for Chelsea in 2019Manchester United are set to make a third bid of about £55m for Chelsea midfielder Mason Mount.
The Old Trafford club will also warn they will walk away from negotiations with the Blues if the offer is not accepted.
Chelsea are thought to value the England international at £70m.
However, United feel that figure is excessive as Mount only has a year left on his contract and talks about an extension have stalled.
United have already had bids worth up to £40m and £50m for Mount rejected by Chelsea.
United boss Erik ten Hag wants Mount to become his first signing of the summer as he looks to strengthen his side following their qualification for next season's Champions League.
Personal terms are not thought to be a problem and United are confident the player wants to make the move to Old Trafford.
Mount, who has scored 33 goals in 195 appearances for Chelsea since making his debut in 2019, missed the end of the domestic season with injury as the Blues came 12th - their lowest finish for more than 25 years.
He won the Champions League in 2021 with Chelsea and started their 1-0 win over Manchester City in the final. He also won the Fifa Club World Cup and Uefa Super Cup with the Blues.
The 24-year-old has been capped 36 times by England, scoring five goals, and was part of manager Gareth Southgate's squad for the 2022 World Cup in Qatar.
Mount came through Chelsea's academy before joining Dutch side Vitesse on loan for the 2017-18 season, scoring nine goals in 29 Eredivisie appearances.
The following campaign he was loaned to Derby County, scoring eight goals in 35 Championship games under manager Frank Lampard as the Rams suffered a 2-1 defeat by Aston Villa in the play-off final.
Upon his return to Chelsea in 2019, Mount made his breakthrough under the newly appointed Lampard and became a key player at Stamford Bridge.
Last month Chelsea appointed former Tottenham boss Mauricio Pochettino as their new manager, replacing interim boss Lampard who took over after Graham Potter was sacked.
