Massimiliano Allegri praised the return to form of Douglas Costa after the Brazilian starred in Juventus' 2-0 victory over SPAL on Saturday.

Juve opened up a nine-point gap at the top of Serie A with the win, Costa unlucky not to join Cristiano Ronaldo and Mario Mandzukic on the scoresheet.

Costa was one of six changes made by Allegri after the international break, the 28-year-old having been hampered by an ankle injury earlier in the campaign.

"He started the season well," Allegri told Sky Sport Italia.

"Then he had a bit of rough period due to injuries and other issues, but he's doing well.

"He put in a good performance this evening, above all in terms of personality."

Juve now turn their attention to the Champions League, with the Bianconeri only needing a point against Valencia to secure their progression from Group H.

"Now we are preparing for Tuesday," said defender Leonardo Bonucci. "We can close the qualifying and then play for first place against Young Boys."