Goalkeeper Smith only joined on loan from Nottingham Forest this morning, but the 31-year-old goes straight into the starting line-up ahead of Connor Ripley.
Smallwood, a 20-year-old midfielder from Redcar, has made three substitute appearances this season, but tonight will be his first start in a central midfield role.
The Academy product replaces Merouane Zemmama, who drops to the bench after starting at Reading last weekend.
In one further change, Rhys Williams replace Jonathan Grounds to make his first start of the season at centre-half.
MIDDLESBROUGH: Smith; McMahon, Hines, R Williams, Bennett; Robson, Bailey, Smallwood, Taylor; Lita, McDonald.
Subs: Ripley (gk), Haas, Grounds, Tavares, Kink, Zemmama, Emnes.
DERBY: Fielding; Brayford, Barker, Ayala, Roberts; Doyle, Addison, Ayala, Pearson; Robinson, Ward.
Subs: Duke (gk), Davies, Savage, Porter, Buxton, Bueno, Davies.
Source: Northern Echo
Source: Northern Echo