Zimbabwe lost Kevin Kasuza to another concussion while a brilliant performance from Sikandar Raza put them in control of the second Test against Sri Lanka on a dramatic third day in Harare.

When rain halted play, Zimbabwe were on 62-1 for their second innings, with a lead of 175 runs.

All-rounder Raza had earlier taken 7-113, the second-best figures recorded by a Zimbabwe player in Test cricket as Sri Lanka were all out for 293.

Paul Strang's record of 8-109, achieved against New Zealand in 2000, is the country's only superior bowling performance.

But enjoyment of Zimbabwe's progress was tempered by concern over Kasuza, who was taken off the field on a stretcher and rushed to hospital after being hit flush on the helmet by a Kusal Mendis shot at short leg early in the day.

He was diagnosed with a mild concussion and replaced by Timycen Maruma.

Kasuza is in a stable condition but will continue to be monitored, having also suffered a delayed concussion while fielding at the same position against the same batsman in the first Test, which was his debut.

With Sri Lanka beginning Wednesday on 122-2, Mendis, who had twice been dropped off the bowling of Raza on day two, finally fell to the same bowler for 22.

Kasuza sustained his injury when the pull shot from Mendis struck him, with Carl Mumba gathering the rebound.

Dinesh Chandimal hit Raza for six but they were the only runs he scored before being caught and bowled by the spinner two balls later.

Angelo Mathews (64) played an anchoring role to free up Dhananjaya de Silva (42) as the pair went about rebuilding Sri Lanka's innings.

De Silva had five fours and a six but ended up on his rear end as he was bowled by the rampant Raza in the last over before lunch with a delivery that stayed low.

Raza brought up his five-for by trapping Niroshan Dickwella (1), with a 38 from Vishwa Fernando the only contribution of note from the tail after Mathews had been caught down the legside.

Craig Ervine (13) stepped into open in the absence of Kasuza and he was the only man to fall before the close, with Prince Masvaure (26 not out) and Regis Chakabva (14no) well placed to press home Zimbabwe's advantage.