Sarri said: "He played for three matches in a row. It's normal for a player to play three matches and then rest for one, otherwise we could have a squad with only 13 or 14 players", he added.
'The best situation this evening is the result.
Sarri praised the "important" Giroud and insisted that the striker is "very, very useful" for the team even when he is not among the goals.
"Cesc Fabregas is a great player but Kovacic gives Chelsea what Cesc can't do, and that is drive and take players out of the game from a central position".
"From our doctor, there is no risk [to select him]", Sarri said. There was all the conditions to play very badly, for the cold, for the opponents, for the pitch, for everything.More news: Thousand Oaks shooting: 'Hero' policeman Sergeant Ron Helus among 12 killed
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As a result, Sarri believes it is best for him to play in Borisov and regain his rhythm. I didn't like the first half. We moved the ball only horizontal and slowly.
The Belgium worldwide has played only 26 minutes in the Blues' last four games after suffering the back problem against Manchester United last month, coming on as a second-half substitute in Saturday's 3-1 win over Crystal Palace.
"Better in the first 20, 25 minutes in the second half".
Last term he played well for Crystal Palace, and has also made his mark at worldwide level.
'But I don't want him to be anxious about scoring because, for us, he's very important and very useful.
"I was hoping to score soon because I came back late from the World Cup and I was lacking maybe a bit of efficiency and luck but you always need to keep working hard and keep the faith and that's what happened tonight", France striker Giroud told BT Sport. I think we didn't play very well, I didn't like the first half because we moved the ball only horizontally and slowly, so it was hard to be unsafe.