diff --git a/internal/handlers/handler_authz_grpc.go b/internal/handlers/handler_authz_grpc.go
index dc5103896..3048d433d 100644
--- a/internal/handlers/handler_authz_grpc.go
+++ b/internal/handlers/handler_authz_grpc.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net"
 	"net/url"
+	"strings"
 
 	"github.com/authelia/authelia/v4/internal/authorization"
 	"github.com/authelia/authelia/v4/internal/configuration/schema"
@@ -37,7 +38,7 @@ func NewAuthzGRCP(config *schema.Configuration, providers middlewares.Providers)
 	authBuilder := NewAuthzBuilder().WithConfig(config)
 
 	// Only the following strategies are supported. These are hardcoded at the moment and won't be taken from the configuration
-	strategies := []AuthnStrategy{NewHeaderAuthorizationAuthnStrategy(), NewCookieSessionAuthnStrategy(authBuilder.config.RefreshInterval)}
+	strategies := []AuthnStrategy{NewHeaderProxyAuthorizationAuthnStrategy() /* NewHeaderAuthorizationAuthnStrategy(), */, NewCookieSessionAuthnStrategy(authBuilder.config.RefreshInterval)}
 
 	return &AuthzGRCP{
 		Config:         config,
@@ -260,11 +261,10 @@ func (authz *AuthzGRCP) GetHttpCtxFromGRPC(req *autha.CheckRequest) (*fasthttp.R
 	rtc.Request.Header.Set(fasthttp.HeaderXForwardedFor, data.RemoteHost)
 
 	// Needed for NewHeaderProxyAuthorizationAuthnStrategy and NewHeaderAuthorizationAuthnStrategy
-	if val, isSet := headers["authorization"]; isSet {
-		rtc.Request.Header.Set(fasthttp.HeaderAuthorization, val)
-	}
-	rtc.Request.Header.Set(fasthttp.HeaderProxyAuthorization, headers[fasthttp.HeaderProxyAuthorization])
-	rtc.Request.Header.Set(fasthttp.HeaderWWWAuthenticate, headers[fasthttp.HeaderWWWAuthenticate])
+	authz.setHeaderIfSet(fasthttp.HeaderAuthorization, rtc, &headers)
+	authz.setHeaderIfSet(fasthttp.HeaderProxyAuthorization, rtc, &headers)
+	authz.setHeaderIfSet(fasthttp.HeaderWWWAuthenticate, rtc, &headers)
+	authz.setHeaderIfSet(fasthttp.HeaderProxyAuthenticate, rtc, &headers)
 
 	// Needed for CookieSesseionauthnStrategy
 	rtc.Request.Header.Set("cookie", headers["cookie"])
@@ -272,6 +272,17 @@ func (authz *AuthzGRCP) GetHttpCtxFromGRPC(req *autha.CheckRequest) (*fasthttp.R
 	return rtc, data
 }
 
+// setHeaderIfSet sets the header in the given fastHttp request if the header from the envoy authentication
+// request was also set
+func (authz *AuthzGRCP) setHeaderIfSet(headerKeyFast string, rtc *fasthttp.RequestCtx, envoyHeaders *map[string]string) {
+	// Envoys provided header keys are always lower case
+	envoyHeaderKey := strings.ToLower(headerKeyFast)
+
+	if val, isSet := (*envoyHeaders)[envoyHeaderKey]; isSet {
+		rtc.Request.Header.Set(headerKeyFast, val)
+	}
+}
+
 // ErrAuthResponse returns an authentication error for envoy with the given status code
 // and the given text body
 func (authz *AuthzGRCP) ErrAuthResponse(statuscode envoy_type.StatusCode, body string) *autha.CheckResponse {