Lees failed a fitness test on Friday which rendered the central defender unavailable for the 1-0 win over Wigan and Sasso stepped up for what was just his second start of the campaign.
While Carvalhal is expecting Lees, and Morgan Fox who also missed the match, to recover sufficiently and reclaim his place in the backline for the visit of the Blues, the Owls head coach praised Sasso's performance in helping to keep yet another clean sheet.
"Tom did a test (on Friday) and so did Fox," explained Carvalhal. "They both had problems. We believe they will recover for the next game but they weren't available. Sasso played and he played well. We believe in him 100 per cent. He's not had many chances because Glenn and Tom have done well.
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"He's a player who I know very well. I brought him here. He's not had too many chances because Tom and Glenn have done very well."