The Glassgirls, of the fifth-tier West Midlands Premier, have made it through three ties so far and this is their longest-ever run in the competition.
They saw off Solihull Sporting Ladies and Derby County Women before digging in deep to beat Cambridge City Ladies 2-1 last weekend.
And this will be their toughest test yet as United, who are ninth in the FA Women's Championship, head to the War Memorial Ground (1pm).
Tickets are priced at £6 for adults and just £1 for children under the age of 12.
Also in the Cup, Albion Women are looking to get past Long Eaton United LFC.
The Baggies have enjoyed comprehensive victories in each of the last two rounds – thrashing Crewe 5-0 before beating Lincoln United 4-1.
Stoke City LFC face Nottingham Forest, who knocked out Wolves Women with an emphatic 4-0 victory in the previous round.
Winners in the third round will receive £1,250 from the Cup prize fund, with the losers getting £315.
Back to league matters, in the top-tier Super League, Aston Villa Women are out to snap a three-match losing streak.
They face Tottenham Hotspur in a 6pm kick-off at the Banks's Stadium.
Villa go into it with more confidence after putting seven past Sunderland in the Conti Cup last weekend.
Birmingham City Women remain winless and take on Manchester City.
In the National League Northern Premier, Wolves Women are looking to bounce back from their Cup disappointment and keep their unbeaten league run intact.
Dan McNamara's lot travel to Hull City Ladies (2pm), having already beaten them twice this campaign.
Sporting Khalsa Women, in the National League Division One Midlands, welcome Peterborough United to the Aspray Arena.
A win for Khalsa would be their fourth league triumph in a row.
In the West Midlands Premier, Kidderminster Harriers Women play bottom-of-the-table City of Stoke.
Lye Town Ladies, after the agony of falling to a 95th-minute penalty against Northampton Town in the Cup, go to Sutton Coldfield Town.
Lichfield City Ladies make the short trip to Tamworth.
Sandwell Ladies TREC would love to clinch a statement victory as they host table-toppers Shifnal Town in the West Midlands Division One North.
Walsall Ladies will fancy their chances against rock-bottom Coventry City, while Wyrley Ladies go to AFC Telford United.
An all-local encounter sees Walsall Wood Ladies take on Darlaston Town 1874.
And in the West Midlands Division One South, Sedgley & Gornal United Women are at struggling Droitwich Spa.