Gasol, 34, is averaging 15.7 points, 8.6 rebounds and a career-high 4.7 assists (which ranks second among National Basketball Association centers, trailing only Nikola Jokic's 7.7).
Valanciunas was cleared to play today after missing 25 games with a dislocated left thumb and was expected in Toronto's lineup for Thursday's game at Atlanta.
Gasol also has a $25.6 million player option for next season.
Ujiri's biggest trade deadline moves came in 2017, when he acquired Serge Ibaka from the Orlando Magic and P.J. Tucker from the Phoenix Suns.
Gasol, meanwhile, could be in the Raptors' lineup Saturday in NY pending a team physical.
He said the Raps didn't make a move just to react to rivals Milwaukee and Philadelphia powering up in recent days.More news: Adam Levine likened to an 'awkward stripper' during Super Bowl performance
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Several players seem to be drawing extra attention from the Raptors, who have to fill both the centre slot vacated by Monroe and need extra depth on the wings after losing Wright and Miles.
Toronto played short-handed due to the trades Thursday night but still pulled out a 119-101 win over the Hawks.
"I think that there's a lot of positives with a guy like Gasol, and I think majority come with being battle-tested", Nurse said. After a bit of a slow start to the day, we've got our first really big trade of the day. Yes, they offered me something similar, but I did not want to finish assistant-coach.
Even though Gasol is not the same defensive player he once was, this is a fascinating gamble for the Raptors, who are clearly all-in on winning the Eastern Conference.
In just under 20 minutes per game, Lin is averaging 10.6 points and 3.5 assists on 46.5 per cent shooting (32.5 per cent from three-point range) this season.
Valanciunas is averaging 12.8 points and 7.2 rebounds this season with the Raptors.