UK chief negotiator David Frost and his European Union counterpart, Michel Barnier, remain deadlocked over the remaining crucial issues that could see a trade deal passed by New Year's Eve or derail negotiations under a no-deal Brexit.
Sputnik takes a closer look at the three controversial issues between both sides.
UK Fishing Water Rights
A major row over UK fishing water rights and "level playing field" on regulations could block a potential agreement over the next few days.
The UK negotiating side has demanded 80 percent of fishing stocks from its waters, more than quadruple the 18 percent proposed by Brussels, according to reports.
British vs European Regulations
Further sticking points between the two sides include workers' rights, environmental protections as well as contributions for trade with the single market.
But Brussels has demanded the UK follow European market rules compared with countries such as Canada, or face a tit-for-tat trade war which could increasing tariffs and trade restrictions.
Further concerns Britain's rejection of the European Court of Justice have intensified disagreements in bilateral talks.
UK Internal Market Bill
A major sticking point is Westminster's Internal Market Bill, which has returned to Commons on Monday and could spark fresh disagreements over London's alleged violation of international law.
Commons is set to vote on amendments from the House of Lords and could inflame tensions in negotiations over the contentious Irish backstop, as well as further bills on taxation set to harden the EU's stance on post-Brexit relations.