The 29-year-old Brazilian penned a two-and-a-half year deal with Saints on Thursday after joining on loan from Serie A outfit Cesena in the summer.
Guly has become an increasingly important member of Nigel Adkins' side and has established a potent-looking strikeforce with Lambert, who was delighted to hear the forward is staying on the south coast.
"That's brilliant news," he told Press Association Sport. "There was talk a couple of weeks back that he might not even stay, but I think after speaking to him and the manager we all kind of knew he was going to sign."
Speaking on their ever-improving relationship, Lambert added: "I think I am starting to understand how he plays and he is starting to understand how I play, as well as the rest of the team and the league itself.
"Obviously it takes a bit of time for any partnership to work, especially when it's a Brazilian who has been playing in Italy. To expect us to gel straight away would never work but we're starting to look good now."
Source: PA
Source: PA