The former Italian international defender has battled a nagging adductor injury since the third game of the Major League Soccer season, but looks ready to play again.
"He was in good spirits because he was back with the group," coach Marco Schallibaum said Thursday. "It shows he wants to play, and that experience and quality he has is a big plus for us."
Schallibaum keeps his starting lineup secret, but Nesta should be back in his central defence pairing with fellow Italian Matteo Ferrari when the Impact (6-2-2) end a 10-day break with a home game against the Philadelphia Union on Saturday night.
They should also have fullback Jeb Brovsky, who has been wearing a mask to protect a nose broken in six places when he went up for a header in a Voyageurs Cup match against Vancouver on May 15.
Montreal remains without defenders Nelson Rivas (knee) and Maxim Tissot (fractured toe), midfielders Davy Arnaud (concussion) and Andrea Pisanu (thigh) and forward Daniele Paponi (thigh).
And defender Hassoun Camara, who helped fill Nesta's spot on defence, left practice early Thursday. Schallibaum said he was only tired and should be ready to play on Saturday.
The rangy Nesta may have slowed a step as he nears the end of his storied career, but he remains a leader and a presence on the pitch for the Impact.
Just ask Patrice Bernier, the veteran midfielder who works closely with the defence to recover balls and start the attack.
"It's Alessandro Nesta," Bernier said. "It's good for our team that we kept on doing well when he was gone, but he has that aura, that leadership.
"He's calm on the ball, so it's not necessary for me to always drop back and get the ball. It allows me to concentrate more on my offensive play and what's ahead of me."
Nesta played 19 seasons in Italy with Lazio and AC Milan and made 78 appearances for Italy, including three World Cup campaigns. Considered one of the top central defenders of his era, Nesta was named four times to Europe's best 11 squad.
Surprisingly, the Impact got him without making him a Designated Player, or one who makes more than the top rate under the league's salary cap. Nesta said when he joined the club last summer that money didn't matter and that he wanted to experience MLS along with former Italy teammate Marco Di Vaio, the team's only DP.
He got into eight games at the end of 2012 and played the first three this season before he was forced to leave a game March 16 against Toronto only 12 minutes in. He returned three games later to face Columbus and Chicago before he was sidelined again for three games.
With Ferrari also missing three games with an injury, Schallibaum was forced to experiment with his back line, with Brovsky and Camara carrying most of the load. Youngsters Karl Ouimette, Wandrille Lefevre and Tissot saw playing time.
But they are glad to have Nesta back.
"He's a general, not only with his play but he also talks to make sure everybody is focused," Bernier said. "And it's nice also to have another (experienced) person because it's a great 1-2 with Matteo, but when you're three it's even better."
Swiss fullback Dennis Iapichino, whose play has picked up after a rocky start, may remain at left back with Brovsky on the right, unless Camara plays.
A busy week awaits.
After Saturday's game, the Impact fly to Vancouver for the second leg of their Amway Canadian Championship series. Montreal will then visit Kansas City on June 1.