Striker Webber missed last weekend's 4-2 win over Derby due to a hamstring strain, while midfielder Montgomery was sidelined through illness. Both may have to settle for a place on the substitutes' bench.
Greg Halford has shaken off tonsilitis and is pushing for a return to the starting line-up, while Blackwell has no new injury or suspension worries as his side look to extend their unbeaten league run to seven matches.
Blackwell must decide whether to stick with John-Joe O'Toole, on loan from Watford, in midfield or recall Brian Howard, while Jamie Ward is likely to start up front alongside Darius Henderson, whose two goals against Derby last week took his tally to six for the season.
Cardiff boss Dave Jones looks set to have utility player Mark Kennedy available.
Kennedy has been struggling with a hamstring injury but was an unused substitute in Wednesday's 2-1 home win over Watford and could now push for a return to the starting line-up.
Jay Bothroyd proved his fitness after a calf injury by scoring against the Hornets and he looks set to retain his place up front alongside Ross McCormack.
On-loan goalkeeper Stuart Taylor and midfielder Stephen McPhail should also keep their places in the side as the Bluebirds bid to enhance their promotion credentials.
Ninian Park has become a fortress to Cardiff in recent months and Jones said: "It's not always about performance now - it's about winning games."
Sporting Life