Second Division side Ross County caused a cup upset with a two-goal salvo at Dens Park.
Andy Barrowman scored the opener from the penalty spot in the 12th-minute after Gary MacKenzie brought down Martin Scott inside the area.
County edged further ahead two minutes before half-time when Keddie glanced home a header from Derek Adams' corner.
Jani Sturm reduced the deficit, but the home side could not find an equaliser and had David O'Brien sent off late on.
Dundee: Samson, Forsyth, MacKenzie, Griffin, Clark (Milne 88), O'Brien, Rae, McHale, Sturm, Deasley (Worrell 46), Lyle. Subs Not Used: Burns, Elvin, Roy.
Sent Off: O'Brien (90).
Booked: Sturm, O'Brien.
Goals: Sturm 59.
Ross County: Bullock (Cartis 70), McCulloch, Dowie, Keddie, Golabek, Scott, Iain Anderson (Higgins 87), Adams, Brady, Barrowman, Petrie (Moore 77). Subs Not Used: Webb, Robertson.
Booked: Adams, Dowie, Brady.
Goals: Barrowman 12 pen, Keddie 43.
Ref: D McDonald