The Millers were behind at the break but second half goals from Jerry Yates (penalty) and substitute Richie Smallwood ensured the Millers made a positive start to their stay at Hotel Remes.
Manager Alan Stubbs again used a full range of players with four trialists given the opportunity to try and earn a contract. There was also a sprinkling of development players as the Millers staff enjoyed a lengthy look at their current squad.
After a slow start in muggy conditions the Millers created the first opening on 17 minutes. After good work down the left involving first-year professional Darnelle Bailey-King, the ball was eventually rolled into the path of trialist who fired over from 20 yards.
Two minutes later Greg Halford played in a pinpoint pass to split the Legnica defence to find Yates, but a last ditch challenge denied the youngster who was almost clear on goal.
Bailey-King again showed his pace just before the interval before being upended. The resulting free-kick from Anthony Forde was rolled short to trailist who blasted over the bar.
New signing Forde showed great fleet of foot to skip away down the left but his left-footed teasing cross was cleared away at the near post.
On 33 minutes the Polish side took the lead when a pass from the left found the Legnica striker who rounded the Millers ‘keeper before coolly slotting into the empty net.
Ten minutes before the break the Millers registered their best chance when trialist’s deflected shot was held by the Legnica ‘keeper from 20 yards.
Half-time: Rotherham 0 v 1 Miedz Legnica
The Millers imposed themselves in the second half and visibly upped the tempo.
On 54 minutes they were rewarded when trialist’s ball into Yates resulted in the striker being felled in the area, and Yates himself took the spot kick which he placed beyond the ‘keeper into the bottom right corner.
Manager Alan Stubbs then introduced Stephen Kelly, Richard Wood and Smallwood, in place of Halford, Kirk Broadfoot and Tom Thorpe.
Soon after the Millers took the lead. Trialist made good progress down the right before cutting the ball back to the onrushing Smallwood who side-footed the ball into the top corner.
Full-time: Rotherham 2 v 1 Miedz Legnica
Rotherham: Trialist (Bilboe); Trialist, Broadfoot (Wood), Thorpe (Kelly), Warren (Dawson), Bailey-King, Trialist, Halford (Smallwood), Trialist, Forde, Yates (Muskwe).