diff --git a/src/custom-sort/matchers.ts b/src/custom-sort/matchers.ts
index 7d604d7..2cf55cb 100644
--- a/src/custom-sort/matchers.ts
+++ b/src/custom-sort/matchers.ts
@@ -10,14 +10,14 @@ export const NumberRegexStr: string = ' *(\\d+)';  // Plain number
 export const CompoundNumberDotRegexStr: string = ' *(\\d+(?:\\.\\d+)*)'; // Compound number with dot as separator
 export const CompoundNumberDashRegexStr: string = ' *(\\d+(?:-\\d+)*)'; // Compound number with dash as separator
 
-export const Date_yyyy_mm_dd_RegexStr: string = ' *(\\d{4}-\\d{2}-\\d{2})'
+export const Date_yyyy_mm_dd_RegexStr: string = ' *(\\d{4}-[0-3]*[0-9]-[0-3]*[0-9])'
 export const Date_yyyy_dd_mm_RegexStr: string = Date_yyyy_mm_dd_RegexStr
 
 export const Date_dd_Mmm_yyyy_RegexStr: string = ' *([0-3]*[0-9]-(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)-\\d{4})'; // Date like 01-Jan-2020
 export const Date_Mmm_dd_yyyy_RegexStr: string = ' *((?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)-[0-3]*[0-9]-\\d{4})'; // Date like Jan-01-2020
 
-export const Date_yyyy_Www_mm_dd_RegexStr: string = ' *(\\d{4}-W\\d{1,2} \\(\\d{2}-\\d{2}\\))'
-export const Date_yyyy_WwwISO_RegexStr: string = ' *(\\d{4}-W\\d{1,2})'
+export const Date_yyyy_Www_mm_dd_RegexStr: string = ' *(\\d{4}-W[0-5]*[0-9] \\([0-3]*[0-9]-[0-3]*[0-9]\\))'
+export const Date_yyyy_WwwISO_RegexStr: string = ' *(\\d{4}-W[0-5]*[0-9])'
 export const Date_yyyy_Www_RegexStr: string = Date_yyyy_WwwISO_RegexStr
 
 export const DOT_SEPARATOR = '.'
diff --git a/src/test/unit/sorting-spec-processor.spec.ts b/src/test/unit/sorting-spec-processor.spec.ts
index ec6c026..a83a462 100644
--- a/src/test/unit/sorting-spec-processor.spec.ts
+++ b/src/test/unit/sorting-spec-processor.spec.ts
@@ -7,6 +7,8 @@ import {
 	convertPlainStringToRegex,
 	Date_dd_Mmm_yyyy_NormalizerFn,
 	Date_Mmm_dd_yyyy_NormalizerFn,
+	Date_yyyy_dd_mm_NormalizerFn,
+	Date_yyyy_mm_dd_NormalizerFn,
 	Date_yyyy_Www_mm_dd_NormalizerFn,
 	Date_yyyy_Www_NormalizerFn,
 	Date_yyyy_WwwISO_NormalizerFn,
@@ -383,6 +385,8 @@ Here goes ASCII word \\a+
 \\[yyyy-Www (mm-dd)] Week number ignored
 Week number interpreted in ISO standard \\[yyyy-WwwISO]
 Week number interpreted in U.S. standard \\[yyyy-Www]
+\\[yyyy-mm-dd] plain spec 1
+\\[yyyy-dd-mm] plain spec 2
 `
 
 const expectedSortSpecsExampleSortingSymbols: { [key: string]: CustomSortSpec } = {
@@ -448,26 +452,38 @@ const expectedSortSpecsExampleSortingSymbols: { [key: string]: CustomSortSpec }
 		}, {
 			type: CustomSortGroupType.ExactName,
 			regexPrefix: {
-				regex: /^ *(\d{4}-W\d{1,2} \(\d{2}-\d{2}\)) Week number ignored$/i,
+				regex: /^ *(\d{4}-W[0-5]*[0-9] \([0-3]*[0-9]-[0-3]*[0-9]\)) Week number ignored$/i,
 				normalizerFn: Date_yyyy_Www_mm_dd_NormalizerFn
 			}
 		}, {
 			type: CustomSortGroupType.ExactName,
 			regexPrefix: {
-				regex: /^Week number interpreted in ISO standard  *(\d{4}-W\d{1,2})$/i,
+				regex: /^Week number interpreted in ISO standard  *(\d{4}-W[0-5]*[0-9])$/i,
 				normalizerFn: Date_yyyy_WwwISO_NormalizerFn
 			}
 		}, {
 			type: CustomSortGroupType.ExactName,
 			regexPrefix: {
-				regex: /^Week number interpreted in U\.S\. standard  *(\d{4}-W\d{1,2})$/i,
+				regex: /^Week number interpreted in U\.S\. standard  *(\d{4}-W[0-5]*[0-9])$/i,
 				normalizerFn: Date_yyyy_Www_NormalizerFn
 			}
+		}, {
+			type: CustomSortGroupType.ExactName,
+			regexPrefix: {
+				regex: /^ *(\d{4}-[0-3]*[0-9]-[0-3]*[0-9]) plain spec 1$/i,
+				normalizerFn: Date_yyyy_mm_dd_NormalizerFn
+			}
+		}, {
+			type: CustomSortGroupType.ExactName,
+			regexPrefix: {
+				regex: /^ *(\d{4}-[0-3]*[0-9]-[0-3]*[0-9]) plain spec 2$/i,
+				normalizerFn: Date_yyyy_dd_mm_NormalizerFn
+			}
 		}, {
 			type: CustomSortGroupType.Outsiders
 		}],
 		targetFoldersPaths: ['mock-folder'],
-		outsidersGroupIdx: 12
+		outsidersGroupIdx: 14
 	}
 }