The midfielder helped the Light Blues get off to a flying start during their Scottish Cup tie with Dundee.
The 25-year-old helped Mark Warburton's men start their Scottish Cup quarter-final tie with Premiership side Dundee in incredible fashion as he fired home the opening goal just 13 seconds into the clash at Ibrox.
And Wallace - who rounded off the 4-0 victory with the final goal - admitted that he was delighted for the former Doncaster man.
"I'm really pleased for Harry in particular. He is another one who has come in and added tremendous work ethic. He has added real value on and off the pitch. He's a great lad, very down to earth, and he's now getting his rewards for his hard work on the pitch," he told the Evening Times.
"He can play anywhere across the front. Seven, nine, 10 or 11 and can perform well too. He's obviously a very technically gifted player as we've seen with his goals. He's done really well and there's a lot more to come from him."
Despite enduring a fairly slow start to life since his move to Rangers, the strike against Paul Hartley's men was Forrester's third in as many games as he previously bagged the late winner in the Scottish Championship clash with St Mirren and got the opener in the 2-0 victory over Raith, which helped send Warburton's men even further clear at the top of the table.
And with his thunderous strike setting the Gers well on their way to booking their spot in the last four of the Scottish Cup, he will be hoping that he can continue to contribute important goals that not only help the club seal their return to the top flight, but perhaps also guide the team towards cup glory.